Re: Doubling a Micro Bottom

I'm weighing the pros and cons of the suggested methods. I'll post my decision and results when I have them. Thanks for all the suggestions this group is an amazing resource. My immediate task is to get the Lexan windows installed and a sliding roof hatch built so that the interior will be in the dry. I'm tired of tarping and un-tarping the boat when I want to work on it.

--- Inbolger@yahoogroups.com, "MylesJ. Swift" <mswift@...> wrote:
>
> The ring shank nails don't seem to get much love anymore. They are cheap
> enough, apply good pressure in areas you can't get a clamp on. They work
> well for people like me that don't have a big clamp collection. As Bruce
> says they are easy to sand over without wiping out the paper. Plus you can
> keep working instead of having to wait to for fillets to harden.
>
>
>
> MylesJ
>

The ring shank nails don’t seem to get much love anymore. They are cheap enough, apply good pressure in areas you can’t get a clamp on. They work well for people like me that don’t have a big clamp collection. As Bruce says they are easy to sand over without wiping out the paper. Plus you can keep working instead of having to wait to for fillets to harden.

 

MylesJ

Sand to wood. Coat the new and old bottom, where they are to be glued together, with un-thicken (and not thinned) epoxy. Allow to dry until both are tacky, if any areas appear to have absorbed all of the epoxy, recover both pieces to be glued without sanding. Put on thicken epoxy on surface of first coated piece as it will be drier. Use a toothed applicator like is used with tile mastic for applying thicken epoxy. Now place new bottom on. Clamp as well as you can, using any or several of the suggestions, others have given. Do not clamp too hard, you do not want to squeeze out all of the epoxy. Since both boards are protected by the un-thicken epoxy any small voids shouldn't cause rot any problems.


--- Inbolger@yahoogroups.com, "Kendall" <ken_j_@...> wrote:
>
> I just picked up my micro navigator over the weekend. The bottom of the boat is built to plans at 1/4" plywood and it has been patched a couple of times and is checking in places. I was wanting to get the bottom to 12" minimum or possibly 3/4" or 1" anyway. Can I epoxy some new plywood directly to the existing and then glass over that or should I remove what's there and start from scratch? The bottom is solid with out any soft spots and once I get all the paint removed I will do an inspection and replace any questionable sections if found. My reason for doubling the bottom is that I sail in a water reservoir and the level is constantly changing. It's a man made and there are lots of submerged trees that can get to just below the surface during low water periods.
>
Thinking about the original question I see two issues which need to be addressed:

a) checking of the original floor
b) strengthening the floor in case of impact

a) Most of us would agree that fiberglass cloth in epoxy over a well sanded bottom will deal with the checking as effectively as any other solution. In fact just epoxy probably would, but the fibreglass cloth is relatively inexpensive and worth it for the strengthening anyway.
This can be done with the boat on its side one side at a time with a little care.

b) I think that with a little analysis the critical floor areas could be identified and reinforced from the inside rather than by sheathing the outside. This would give you the possibility of screwing/nailing into the smaller reinforcement panels from the critical areas of the floor rather than attempting the whole re sheath in one go. You can almost certainly screw the center panel into the keel from above


This adds weight low down but does not affect the bottom profile in any way. I can't find plans to the Navigator and, with interiors being up to the owner, actual distribution/access may be more complicated than in theory. I assume you really only need to reinforce the floor of the watertight areas.

David

--- Inbolger@yahoogroups.com, BruceHallman <hallman@...> wrote:
>
> On Wed, Oct 19, 2011 at 8:16 PM, David <dir_cobb@...> wrote:
> >
> >
> >
> > My experience is that even small laminations are not as easy as they look. I managed to get voids gluing a rudder lamination. I hate to think of a full bottom. Weights were no good and screws make lots of holes. It seems much glue is called for.
>
>
> I agree that the clamping of a laminate is very tricky. I was
> surprised and pleased that the lamination process of the bottom of the
> Topaz Spyder went very smoothly. (Vacuum bag might also work fine
> too.)
>
> Here is how I did it with Topaz Spyder: The overall hull bottom is 1
> inch thick, made up of two layers of 1/2" plywood. Averaging about
> 6-7 feet wide by 31 feet overall long. The top and bottom layers were
> staggered by two feet so the joints were staggered.
>
> 1) I positioned the bottom layer on the strong back.
> 2) Then I made a batch of about 1 quart of epoxy, and poured it on 2
> feet of the lower plywood and on 2 feet of the top piece, then spread
> it around with an 10 inch metal 'drywall taping blade.
> 3) I then flipped the top piece and mated the wet glue face to face.
> 4) Taking two hammers, a carpenters hammer in my right hand, and a 3
> pound maul in my left hand (held underneath as a 'backer' to keep the
> wood from bouncing), I nailed the two pieces together using 7/8" #14
> silicon bronze ring shank nails at about 10 inch centers.
>
> I am confident that there were zero voids, as the ring shanks cinched
> up real tight. The silicon bronze has the advantage that it is just
> soft enough that you could then follow up with a pass over using a
> belt sander without eating up the belts, to get things smoothed up for
> the surface fiberglass lamination that follows.
>
> For this reason, I am worried about laminating two sheets of 1/4"
> plywood, as it it too thin to accept ring shank nails. Two sheets of
> 1/2" work fine, great even. It was surprising to see how the 2ft
> staggered joint did a great job of giving a "fair curve" bend to the
> sweep of the bottom, credit to PB&F for this design nuance.
>
On Wed, Oct 19, 2011 at 8:16 PM, David <dir_cobb@...> wrote:
>
>
>
> My experience is that even small laminations are not as easy as they look. I managed to get voids gluing a rudder lamination. I hate to think of a full bottom. Weights were no good and screws make lots of holes. It seems much glue is called for.


I agree that the clamping of a laminate is very tricky. I was
surprised and pleased that the lamination process of the bottom of the
Topaz Spyder went very smoothly. (Vacuum bag might also work fine
too.)

Here is how I did it with Topaz Spyder: The overall hull bottom is 1
inch thick, made up of two layers of 1/2" plywood. Averaging about
6-7 feet wide by 31 feet overall long. The top and bottom layers were
staggered by two feet so the joints were staggered.

1) I positioned the bottom layer on the strong back.
2) Then I made a batch of about 1 quart of epoxy, and poured it on 2
feet of the lower plywood and on 2 feet of the top piece, then spread
it around with an 10 inch metal 'drywall taping blade.
3) I then flipped the top piece and mated the wet glue face to face.
4) Taking two hammers, a carpenters hammer in my right hand, and a 3
pound maul in my left hand (held underneath as a 'backer' to keep the
wood from bouncing), I nailed the two pieces together using 7/8" #14
silicon bronze ring shank nails at about 10 inch centers.

I am confident that there were zero voids, as the ring shanks cinched
up real tight. The silicon bronze has the advantage that it is just
soft enough that you could then follow up with a pass over using a
belt sander without eating up the belts, to get things smoothed up for
the surface fiberglass lamination that follows.

For this reason, I am worried about laminating two sheets of 1/4"
plywood, as it it too thin to accept ring shank nails. Two sheets of
1/2" work fine, great even. It was surprising to see how the 2ft
staggered joint did a great job of giving a "fair curve" bend to the
sweep of the bottom, credit to PB&F for this design nuance.
IIRC, Vaitses used staples because at that time he was using POLYESTER resin which ,unlike epoxy, is a POOR adhesive.

Paul T. (who, many years ago, used polyester both with and without staples--neither of which was really satisfactory)

--- Inbolger@yahoogroups.com, "prairiedog2332" <arvent@...> wrote:
>
> If I recall, Vaitses' method for applying the mat to a hull was to
> staple it in place first prior to applying the resin and leave them in,
> obviously not that practical on a 1/4 inch bottom, as you would end up
> with a pincushion inside the hull.
>
> I also recall a discussion one time regarding using non-metallic polymer
> staples. The protruding ends could be easily cut or sanded inside the
> hull I would think.
>
>http://www.raptornails.com/catalog_staples.php
>
> This might be "doable" if the boat could laid on it's side and the resin
> rolled in firmly to fill potential gaps. I know with my skiff it never
> showed any signs of delamination on the outer hull after several years.
> The dagger board housing split when I grounded a few times, water froze
> inside it and it began to leak so I gave it away. The next owner removed
> it and converted it to a motor boat. Still going the last I heard:-)
>
>
>
>
> --- Inbolger@yahoogroups.com, "David" <dir_cobb@> wrote:
> >
> > My experience is that even small laminations are not as easy as they
> look. I managed to get voids gluing a rudder lamination. I hate to think
> of a full bottom. Weights were no good and screws make lots of holes. It
> seems much glue is called for.
>
If I recall, Vaitses' method for applying the mat to a hull was to
staple it in place first prior to applying the resin and leave them in,
obviously not that practical on a 1/4 inch bottom, as you would end up
with a pincushion inside the hull.

I also recall a discussion one time regarding using non-metallic polymer
staples. The protruding ends could be easily cut or sanded inside the
hull I would think.

http://www.raptornails.com/catalog_staples.php

This might be "doable" if the boat could laid on it's side and the resin
rolled in firmly to fill potential gaps. I know with my skiff it never
showed any signs of delamination on the outer hull after several years.
The dagger board housing split when I grounded a few times, water froze
inside it and it began to leak so I gave it away. The next owner removed
it and converted it to a motor boat. Still going the last I heard:-)




--- Inbolger@yahoogroups.com, "David" <dir_cobb@...> wrote:
>
> My experience is that even small laminations are not as easy as they
look. I managed to get voids gluing a rudder lamination. I hate to think
of a full bottom. Weights were no good and screws make lots of holes. It
seems much glue is called for.
My experience is that even small laminations are not as easy as they look. I managed to get voids gluing a rudder lamination. I hate to think of a full bottom. Weights were no good and screws make lots of holes. It seems much glue is called for.

A neat solution would be to use a vacuum bag (as used by Nexus Marine building the Black Skimmer -http://www.nexusmarine.com/skimmer_construction.html)

However, I tend to agree that if it's strength you are after with a reasonable sound structure, at this stage in the life of the boat, it is probably better to fibreglass the bottom (which you can do in halfs - from each side of the keel case round to over the chine).

If the boat is rotten or severely damaged (I seem to remember a quote somewhere about Bernie Wolfard having to replace the floor of his Micro), that might be the way to go. Just take the floor off completely and rebuild from there down. In that case I would just go for the thickness of floor you intend to use. (I built Oldshoe with a 3/8" floor) Up to 1/2" is probably manageable with help and patience for Micro. Still a lot of work and you will definitely want her upside down... Where do you leave the cabin?...

David


--- Inbolger@yahoogroups.com, "Kendall" <ken_j_@...> wrote:
>
> I just picked up my micro navigator over the weekend. The bottom of the boat is built to plans at 1/4" plywood and it has been patched a couple of times and is checking in places. I was wanting to get the bottom to 12" minimum or possibly 3/4" or 1" anyway. Can I epoxy some new plywood directly to the existing and then glass over that or should I remove what's there and start from scratch? The bottom is solid with out any soft spots and once I get all the paint removed I will do an inspection and replace any questionable sections if found. My reason for doubling the bottom is that I sail in a water reservoir and the level is constantly changing. It's a man made and there are lots of submerged trees that can get to just below the surface during low water periods.
>

Right author but wrong book.

http://www.amazon.com/Covering-Wooden-Boats-Fiberglass-Vaitses/dp/0877429979/ref=sr_1_3?s=books&ie=UTF8&qid=1319056141&sr=1-3

Seems it may be out of print now?


--- In bolger@yahoogroups.com, "prairiedog2332" <arvent@...> wrote:
>
>
> Here is a link to the Vaitses' book. The spelling was incorrect in the
> previous post.
>
> http://www.amazon.ca/Fiberglass-Boat-Repair-Manual/dp/0071569146
> <http://www.amazon.ca/Fiberglass-Boat-Repair-Manual/dp/0071569146>
>
> The method has been roundly criticised when used on large traditionaly
> planked hulls, but on a small plywood boat there are not the same issues
> to deal with.
>
>
> --- In bolger@yahoogroups.com, "prairiedog2332" arvent@ wrote:
> >
> >
> > Kendall,
> >
> > If you can get the boat on it's side, as described by Myles, a
> possible
> > option might be to add a layer of fiberglass mat instead of plywood.
> > Description here:
> >
> > http://www.noahsboatbuilding.com/noahmain/itemdesc.asp?ic=1X38&eq=&Tp
> >
> <http://www.noahsboatbuilding.com/noahmain/itemdesc.asp?ic=1X38&eq=&Tp>
> > =
> >
> > It soaks up a lot of resin but polyester will work with it. Then it is
> > faired using bondo and can be glassed over with regular cloth. I had a
> > sailing skiff that the outside of the hull was re-done that way due to
> > checking and does work. Adds a considerable amount of weight but that
> is
> > not a problem on a Micro.
> >
> > I think Allan Vaites has a book out about doing that.
> >
> > Nels
>

Here is a link to the Vaitses' book. The spelling was incorrect in the previous post.

http://www.amazon.ca/Fiberglass-Boat-Repair-Manual/dp/0071569146

The method has been roundly criticised when used on large traditionaly planked hulls, but on a small plywood boat there are not the same issues to deal with.


--- In bolger@yahoogroups.com, "prairiedog2332" <arvent@...> wrote:
>
>
> Kendall,
>
> If you can get the boat on it's side, as described by Myles, a possible
> option might be to add a layer of fiberglass mat instead of plywood.
> Description here:
>
> http://www.noahsboatbuilding.com/noahmain/itemdesc.asp?ic=1X38&eq=&Tp
> <http://www.noahsboatbuilding.com/noahmain/itemdesc.asp?ic=1X38&eq=&Tp>
> =
>
> It soaks up a lot of resin but polyester will work with it. Then it is
> faired using bondo and can be glassed over with regular cloth. I had a
> sailing skiff that the outside of the hull was re-done that way due to
> checking and does work. Adds a considerable amount of weight but that is
> not a problem on a Micro.
>
> I think Allan Vaites has a book out about doing that.
>
> Nels

If it were me, I would seriously consider any way imaginable to avoid
working upside down, and/or working with that 420lbs slug of lead over
my head!


Installing it in the first place took great care, no doubt. But properly supported now, why worry? People work underneath much heavier cars and trucks up on jack stands every day. I never got under there myself unless able to give it all a strong kick and a shove without incident.

The problem with glassing overhead is getting it into your eyes! Yet Myles description of turning a Micro, let alone a Navigator, seems risky enough to me to avoid if possible. Quote here from the System 3 Epoxy Book. 

"Applying fiberglass overhead is at best a difficult, messy job. Anyone who has tried it once has no desire to repeat the experience and will do everything possible to try to turn the boat over or at least work on a slant. If this is not possible here are several suggestions for accomplishing this job:

If you are working on a relatively small area, wet the surface with mixed resin/hardener and lay a rough cut piece of cloth into the resin. Surface tension will hold it into place without sagging if too much resin is not used. Using a squeegee overhead is a feat no one has yet mastered. Use foam rollers. Once the epoxy has cured you finish the overhead area in the usual manner.

Glassing large overhead areas calls for a different technique and a helper or two. Most successful jobs are done by rolling on a coating, then allowing it to cure to a tacky state. The cloth is then rolled as smoothly as possible onto the tacky coating. This is where you'll probably need more than one person. Get the wrinkles out as you go along, you won't be able to slide them out because the tackiness of the coating will hold the cloth in place. Once you've got the cloth where you want it press it into the tacky undercoat with a dry foam roller. When it is all smushed down, wet it out using the roller cover and a roller pan. Use just enough epoxy to wet out the cloth. When cured finish in the usual way.





Kendall,

If you can get the boat on it's side, as described by Myles, a possible option might be to add a layer of fiberglass mat instead of plywood. Description here:

http://www.noahsboatbuilding.com/noahmain/itemdesc.asp?ic=1X38&eq=&Tp=

It soaks up a lot of resin but polyester will work with it. Then it is faired using bondo and can be glassed over with regular cloth. I had a sailing skiff that the outside of the hull was re-done that way due to checking and does work. Adds a considerable amount of weight but that is not a problem on a Micro.

I think Allan Vaites has a book out about doing that.

Nels


--- Inbolger@yahoogroups.com, "Kendall" <ken_j_@...> wrote:
>
> I just picked up my micro navigator over the weekend. The bottom of the boat is built to plans at 1/4" plywood and it has been patched a couple of times and is checking in places. I was wanting to get the bottom to 12" minimum or possibly 3/4" or 1" anyway. Can I epoxy some new plywood directly to the existing and then glass over that or should I remove what's there and start from scratch? The bottom is solid with out any soft spots and once I get all the paint removed I will do an inspection and replace any questionable sections if found. My reason for doubling the bottom is that I sail in a water reservoir and the level is constantly changing. It's a man made and there are lots of submerged trees that can get to just below the surface during low water periods.
>

On Wed, Oct 19, 2011 at 10:14 AM, MylesJ. Swift
<mswift@...> wrote:
>
>
>
> I have gotten Micro on its side using cargo straps, an overhead beam and some mattresses.


Bear in mind that the 420 pounds of lead ballast, compared with
perhaps 400 pound for all the remaining wood in the hull makes the
center of gravity of the assembly very much down low! (Like one of
those 'blow up' punching bags.)


Thinking out of the box, if the hull is checked so drastically that
hull rebuilding is unavoidable, then why not take a 'SawsAll' and
remove the Navigator cabin, and then build a new hull from scratch,
and install that Navigator cabin topsides onto the new hull?

If it were me, I would seriously consider any way imaginable to avoid
working upside down, and/or working with that 420lbs slug of lead over
my head!

I guess I am very old school. Boats have lifespans, and when they are
too old and decrepit, there is an appropriate time to call them dead
and start anew. I am not in the group of people that think old boats
should always be repaired.

I have gotten Micro on its side using cargo straps, an overhead beam and some mattresses. Lift the boat on the cargo straps, pull out the trailer and put the mattresses under. Use a come along to pull it about a foot to the side and let it down until the keel touches. Support the down side with legs like you might when stranded by the tide. Rotate the straps a foot or so, lift the boat clear of the mattress and do it again and again until you have her down on her side. You have to put a line across the boat to cinch the straps to the hull or it will slip when you lift it because the load is off center, and you won’t get anywhere. Same with putting lines between the front and rear lifting straps  to maintain the spacing of those. I used a pair of 5 ton cargo straps with ratchets to do this

 

Myles J. Swift

Computer Assistance Inc.

Helping Independent Auto/Truck Shops Since 1978

Voice 541-895-3347

www.computerassistance.com

 

Scott,

 


Micro was built with resorcinol. I glued and nailed the second sheet onto the bottom. In the larger areas not near a framing piece I face nailed them together with bronze ring shanks. I ground off the protruding parts of the nails after everything was set.

 

Myles J. Swift

Computer Assistance Inc.

Helping Independent Auto/Truck Shops Since 1978

Voice 541-895-3347

www.computerassistance.com

 

I'd think about just going 90 degrees, then living with a somewhat
more difficult but not impossible glass job.


On Oct 18, 2011, at 9:10 PM, Kendall wrote:

> Any thoughts on how to flip this boat for fiber-glassing?
>
Any thoughts on how to flip this boat for fiber-glassing?

--- Inbolger@yahoogroups.com, "prairiedog2332" <arvent@...> wrote:
>
>
> This was discussed awhile back when Susanne inquired as to suggested
> methods to laminate a double layered bottom to a hull.
>
> One method that I recall being suggested was to drill holes in a pattern
> about 6" apart in the outer ply layer and use waxed drywall screws with
> a smooth shank equal to the thickness of the outside layer. Apply
> thickened epoxy to the underlayer and clamp the outer by tightening
> down the screws until epoxy appeared in the holes.
>
> Once everything cures, remove the drywall screws and glass the outer
> layer with enough epoxy to fill the holes and the weave.
>
> I have a bottom to stengthen on a Skimmer and planning to to it that
> way. But it is easy to invert a Skimmer to do that. How you can do that
> with a Micro Navigator hull is something much more complicated I would
> think.
>
>
> --- Inbolger@yahoogroups.com, Scot Mc Pherson <scot.mcpherson@>
> wrote:
> >
> > I doubled the standard ¼ ply on the bottom when I built Micro and I
> ended up
> > doubling the main deck as well after the first season. I'd get
> down to good
> > wood and roll a coat of epoxy on it before putting on the second
> sheet.****
> > -----------------
> >
> > Yes agreed, but you need to make sure you get good even contact with
> the
> > doubled plywood. Voids between laminations will aggregate
> condensation, AND
> > the constant movement will slowly pull the laminations apart. This
> isn't
> > like a knot void in layer of plywood, a void between lamination layers
> will
> > eventually pull the whole lamination apart. You need to somehow clamp
> the
> > whole thing securely and evenly to prevent lamination voids.
> >
> > Scot McPherson, CISSP, MCSA
> > McPherson Family Farms
> > Le Claire, IA, USA
> >
>
Weight alone isn't enough to assure a mating curvature. Progressively applying clamps or screws as mentioned assures the curvature of the 2nd laminate mates with the first.

Scot McPherson
McPherson Family Farms
Le Claire, IA USA
Sent from my iPhone

On Oct 18, 2011, at 6:15 PM, "John and Kathy Trussell" <jtrussell2@...> wrote:

 

Re: clamping the bottom.

 

Epoxy doesn’t require pressure, but voids are a problem. The first way to avoid voids is, as the proprietor of Folbot used to say, “Use plenty glue!”  My standard procedure (which has worked so far) is to coat both surfaces with straight epoxy and then mix up some thickened epoxy (I use saw dust, but there are other thickeners available) and spread it on one of the surfaces. Put the surfaces together and apply some pressure (squeeze out is good, but clean it up before the epoxy gets hard). How to apply pressure? Weight, in the form of cinder blocks works. You can drill holes and tighten things up with nuts and bolts (waxed). When I build glued plywood lapstrake, I use a waxed batten, drill through the batten and the planking (drill bit sized to the outside of the sheet rock screw threads), and drive sheetrock screw into a pre drilled (drill bit sized to the shaft of the screw), waxed wooden “nut”. Any of the clamping methods described is a two person job and some care should be taken not to drive a screw into your partner.

 

There are no doubt other ways, some of which may be better than what I suggest. I assume that the keel will remain in place, so you would only be doing half a side at a time…

 

Have fun.

 

JohnT

 

From:bolger@yahoogroups.com[mailto:bolger@yahoogroups.com]On Behalf Ofprairiedog2332
Sent:Tuesday, October 18, 2011 6:46 PM
To:bolger@yahoogroups.com
Subject:[bolger] Re: Doubling a Micro Bottom

 

 


This was discussed awhile back when Susanne inquired as to suggested
methods to laminate a double layered bottom to a hull.

One method that I recall being suggested was to drill holes in a pattern
about 6" apart in the outer ply layer and use waxed drywall screws with
a smooth shank equal to the thickness of the outside layer. Apply
thickened epoxy to the underlayer and clamp the outer by tightening
down the screws until epoxy appeared in the holes.

Once everything cures, remove the drywall screws and glass the outer
layer with enough epoxy to fill the holes and the weave.

I have a bottom to stengthen on a Skimmer and planning to to it that
way. But it is easy to invert a Skimmer to do that. How you can do that
with a Micro Navigator hull is something much more complicated I would
think.

--- Inbolger@yahoogroups.com, Scot Mc Pherson <scot.mcpherson@...>
wrote:
>
> I doubled the standard ¼ ply on the bottom when I built Micro and I
ended up
> doubling the main deck as well after the first season. I'd get
down to good
> wood and roll a coat of epoxy on it before putting on the second
sheet.****
> -----------------
>
> Yes agreed, but you need to make sure you get good even contact with
the
> doubled plywood. Voids between laminations will aggregate
condensation, AND
> the constant movement will slowly pull the laminations apart. This
isn't
> like a knot void in layer of plywood, a void between lamination layers
will
> eventually pull the whole lamination apart. You need to somehow clamp
the
> whole thing securely and evenly to prevent lamination voids.
>
> Scot McPherson, CISSP, MCSA
> McPherson Family Farms
> Le Claire , IA , USA
>

In many designs, Phil spec'd out laminating two sheet of thinner plywood. However, where he thought appropriate, dynamite respec'd with one sheet of thicker plywood if the ply wasn't too tortured.

Yes laminating two sheets will result in a stronger form because there is less curve tension (think of bending a straw) when you curve one thin sheet then curve another thin sheet on top, but if the curvature isn't so great, then you can get away with one thicker sheet with virtually no loss of structural strength and I agree that this is preferable to failing to mate two laminations perfectly.

Scot McPherson
McPherson Family Farms
Le Claire, IA USA
Sent from my iPhone

On Oct 18, 2011, at 5:45 PM, "prairiedog2332" <arvent@...> wrote:

 


This was discussed awhile back when Susanne inquired as to suggested
methods to laminate a double layered bottom to a hull.

One method that I recall being suggested was to drill holes in a pattern
about 6" apart in the outer ply layer and use waxed drywall screws with
a smooth shank equal to the thickness of the outside layer. Apply
thickened epoxy to the underlayer and clamp the outer by tightening
down the screws until epoxy appeared in the holes.

Once everything cures, remove the drywall screws and glass the outer
layer with enough epoxy to fill the holes and the weave.

I have a bottom to stengthen on a Skimmer and planning to to it that
way. But it is easy to invert a Skimmer to do that. How you can do that
with a Micro Navigator hull is something much more complicated I would
think.

--- Inbolger@yahoogroups.com, Scot Mc Pherson <scot.mcpherson@...>
wrote:
>
> I doubled the standard ¼ ply on the bottom when I built Micro and I
ended up
> doubling the main deck as well after the first season. I'd get
down to good
> wood and roll a coat of epoxy on it before putting on the second
sheet.****
> -----------------
>
> Yes agreed, but you need to make sure you get good even contact with
the
> doubled plywood. Voids between laminations will aggregate
condensation, AND
> the constant movement will slowly pull the laminations apart. This
isn't
> like a knot void in layer of plywood, a void between lamination layers
will
> eventually pull the whole lamination apart. You need to somehow clamp
the
> whole thing securely and evenly to prevent lamination voids.
>
> Scot McPherson, CISSP, MCSA
> McPherson Family Farms
> Le Claire, IA, USA
>

I agree that epoxy does not require a lot of clamping, but bending the
plywood to the hull bottom rocker does as mentioned by Bruce Hallman.
Certainly adding weights like concrete blocks would assist. Having the
screws act as clamps adds a more "even" pressure and would lessen the
chances of voids occuring in my view.

I intend to use both options, but again having the hull inverted makes
both options a lot more viable.

I think with a Micro Navigator one would have to try and do it with the
hull upright. Prepare several lengths of 2x4's that conform to the hull
rocker with a "T' attached to the top to act as vertical clamps. Have
them bolted to a strongback at the bottom. Jack up the keel about an
inch, slide in the plywood that is slathered with slow setting filled
epoxy and lower the jacks. Drive in screws to ensure even pressure. Then
do the other side of the hull.

Lots of work and effort, but may be worth it if the rest of boat is
still sound.

Glassing would only be doable if the hull could then be tilted over to
at least 45 degrees.

--- Inbolger@yahoogroups.com, "John and Kathy Trussell"
<jtrussell2@...> wrote:
>
> Re: clamping the bottom.
>
>
>
> Epoxy doesn't require pressure, but voids are a problem. The first
way to
> avoid voids is, as the proprietor of Folbot used to say, "Use
plenty glue!"
> My standard procedure (which has worked so far) is to coat both
surfaces
> with straight epoxy and then mix up some thickened epoxy (I use saw
dust,
> but there are other thickeners available) and spread it on one of the
> surfaces. Put the surfaces together and apply some pressure (squeeze
out is
> good, but clean it up before the epoxy gets hard). How to apply
pressure?
> Weight, in the form of cinder blocks works. You can drill holes and
tighten
> things up with nuts and bolts (waxed). When I build glued plywood
lapstrake,
> I use a waxed batten, drill through the batten and the planking (drill
bit
> sized to the outside of the sheet rock screw threads), and drive
sheetrock
> screw into a pre drilled (drill bit sized to the shaft of the screw),
waxed
> wooden "nut". Any of the clamping methods described is a two
person job and
> some care should be taken not to drive a screw into your partner.
>
>
>
> There are no doubt other ways, some of which may be better than what I
> suggest. I assume that the keel will remain in place, so you would
only be
> doing half a side at a time…
>
>
>
> Have fun.
>
>
>
> JohnT
>
>
>
> _____
>
> From:bolger@yahoogroups.com[mailto:bolger@yahoogroups.com] On Behalf
Of
> prairiedog2332
> Sent: Tuesday, October 18, 2011 6:46 PM
> To:bolger@yahoogroups.com
> Subject: [bolger] Re: Doubling a Micro Bottom
>
>
>
>
>
>
> This was discussed awhile back when Susanne inquired as to suggested
> methods to laminate a double layered bottom to a hull.
>
> One method that I recall being suggested was to drill holes in a
pattern
> about 6" apart in the outer ply layer and use waxed drywall screws
with
> a smooth shank equal to the thickness of the outside layer. Apply
> thickened epoxy to the underlayer and clamp the outer by tightening
> down the screws until epoxy appeared in the holes.
>
> Once everything cures, remove the drywall screws and glass the outer
> layer with enough epoxy to fill the holes and the weave.
>
> I have a bottom to stengthen on a Skimmer and planning to to it that
> way. But it is easy to invert a Skimmer to do that. How you can do
that
> with a Micro Navigator hull is something much more complicated I would
> think.
>
> --- Inbolger@yahoogroups.com<mailto:bolger%40yahoogroups.com> , Scot
Mc
> Pherson scot.mcpherson@
> wrote:
> >
> > I doubled the standard ¼ ply on the bottom when I built Micro and
I
> ended up
> > doubling the main deck as well after the first season. I'd get
> down to good
> > wood and roll a coat of epoxy on it before putting on the second
> sheet.****
> > -----------------
> >
> > Yes agreed, but you need to make sure you get good even contact with
> the
> > doubled plywood. Voids between laminations will aggregate
> condensation, AND
> > the constant movement will slowly pull the laminations apart. This
> isn't
> > like a knot void in layer of plywood, a void between lamination
layers
> will
> > eventually pull the whole lamination apart. You need to somehow
clamp
> the
> > whole thing securely and evenly to prevent lamination voids.
> >
> > Scot McPherson, CISSP, MCSA
> > McPherson Family Farms
> > Le Claire, IA, USA
> >
>

Re: clamping the bottom.

 

Epoxy doesn’t require pressure, but voids are a problem. The first way to avoid voids is, as the proprietor of Folbot used to say, “Use plenty glue!”  My standard procedure (which has worked so far) is to coat both surfaces with straight epoxy and then mix up some thickened epoxy (I use saw dust, but there are other thickeners available) and spread it on one of the surfaces. Put the surfaces together and apply some pressure (squeeze out is good, but clean it up before the epoxy gets hard). How to apply pressure? Weight, in the form of cinder blocks works. You can drill holes and tighten things up with nuts and bolts (waxed). When I build glued plywood lapstrake, I use a waxed batten, drill through the batten and the planking (drill bit sized to the outside of the sheet rock screw threads), and drive sheetrock screw into a pre drilled (drill bit sized to the shaft of the screw), waxed wooden “nut”. Any of the clamping methods described is a two person job and some care should be taken not to drive a screw into your partner.

 

There are no doubt other ways, some of which may be better than what I suggest. I assume that the keel will remain in place, so you would only be doing half a side at a time…

 

Have fun.

 

JohnT

 

From:bolger@yahoogroups.com [mailto: bolger@yahoogroups.com ]On Behalf Ofprairiedog2332
Sent:Tuesday, October 18, 2011 6:46 PM
To:bolger@yahoogroups.com
Subject:[bolger] Re: Doubling a Micro Bottom

 

 


This was discussed awhile back when Susanne inquired as to suggested
methods to laminate a double layered bottom to a hull.

One method that I recall being suggested was to drill holes in a pattern
about 6" apart in the outer ply layer and use waxed drywall screws with
a smooth shank equal to the thickness of the outside layer. Apply
thickened epoxy to the underlayer and clamp the outer by tightening
down the screws until epoxy appeared in the holes.

Once everything cures, remove the drywall screws and glass the outer
layer with enough epoxy to fill the holes and the weave.

I have a bottom to stengthen on a Skimmer and planning to to it that
way. But it is easy to invert a Skimmer to do that. How you can do that
with a Micro Navigator hull is something much more complicated I would
think.

--- Inbolger@yahoogroups.com, Scot Mc Pherson <scot.mcpherson@...>
wrote:

>
> I doubled the standard ¼ ply on the bottom when I built Micro and I
ended up
> doubling the main deck as well after the first season. I'd get
down to good
> wood and roll a coat of epoxy on it before putting on the second
sheet.****
> -----------------
>
> Yes agreed, but you need to make sure you get good even contact with
the
> doubled plywood. Voids between laminations will aggregate
condensation, AND
> the constant movement will slowly pull the laminations apart. This
isn't
> like a knot void in layer of plywood, a void between lamination layers
will
> eventually pull the whole lamination apart. You need to somehow clamp
the
> whole thing securely and evenly to prevent lamination voids.
>
> Scot McPherson, CISSP, MCSA
> McPherson Family Farms
> Le Claire ,
w:st="on">IA , USA
>

This was discussed awhile back when Susanne inquired as to suggested
methods to laminate a double layered bottom to a hull.

One method that I recall being suggested was to drill holes in a pattern
about 6" apart in the outer ply layer and use waxed drywall screws with
a smooth shank equal to the thickness of the outside layer. Apply
thickened epoxy to the underlayer and clamp the outer by tightening
down the screws until epoxy appeared in the holes.

Once everything cures, remove the drywall screws and glass the outer
layer with enough epoxy to fill the holes and the weave.

I have a bottom to stengthen on a Skimmer and planning to to it that
way. But it is easy to invert a Skimmer to do that. How you can do that
with a Micro Navigator hull is something much more complicated I would
think.


--- Inbolger@yahoogroups.com, Scot Mc Pherson <scot.mcpherson@...>
wrote:
>
> I doubled the standard ¼ ply on the bottom when I built Micro and I
ended up
> doubling the main deck as well after the first season. I'd get
down to good
> wood and roll a coat of epoxy on it before putting on the second
sheet.****
> -----------------
>
> Yes agreed, but you need to make sure you get good even contact with
the
> doubled plywood. Voids between laminations will aggregate
condensation, AND
> the constant movement will slowly pull the laminations apart. This
isn't
> like a knot void in layer of plywood, a void between lamination layers
will
> eventually pull the whole lamination apart. You need to somehow clamp
the
> whole thing securely and evenly to prevent lamination voids.
>
> Scot McPherson, CISSP, MCSA
> McPherson Family Farms
> Le Claire, IA, USA
>

I doubled the standard ¼ ply on the bottom when I built Micro and I ended up doubling the main deck as well after the first season. I’d get down to good wood and roll a coat of epoxy on it before putting on the second sheet.

-----------------
Yes agreed, but you need to make sure you get good even contact with the doubled plywood. Voids between laminations will aggregate condensation, AND the constant movement will slowly pull the laminations apart. This isn't like a knot void in layer of plywood, a void between lamination layers will eventually pull the whole lamination apart. You need to somehow clamp the whole thing securely and evenly to prevent lamination voids.

Scot McPherson, CISSP, MCSA
McPherson Family Farms
Le Claire, IA, USA

I doubled the standard ¼ ply on the bottom when I built Micro and I ended up doubling the main deck as well after the first season. I’d get down to good wood and roll a coat of epoxy on it before putting on the second sheet.

 

Myles J. Swift

Computer Assistance Inc.

Helping Independent Auto/Truck Shops Since 1978

Voice 541-895-3347

www.computerassistance.com

 

I would sand to bare. Prime with epoxy, sand smooth, then apply a layer of 6OZ glass inside and out set in epoxy. That will be plenty strong and help prevent further checking.

David Jost



--- Inbolger@yahoogroups.com, BruceHallman <hallman@...> wrote:
>
> On Mon, Oct 17, 2011 at 4:12 PM, John and Kathy Trussell
> <jtrussell2@...> wrote:
> >
> >
> >
> > I would sand the existing bottom down to bare wood and epoxy another layer over it. I have heard that ¼" ply is a little light for Micro and a couple have been built with 3/8".
>
>
> Mine has a 1/4" plywood bottom and seems to work fine. Bear in mind
> that the bend in the bottom panel is tight, so thicker plywood doesn't
> bend as easy. And, laminating on a curve like that, well it might be
> easy, but maybe not.
>
I built my micro with a 1/2" bottom and had no trouble bending the 16' scarfed panel to fit the curve. I decided to make the cabin top 1/2" as well cuz I'm a big heavy guy and don't want to worry about where to step when I climb up there to wrestle with the mast. When I saw it would be impossible to get 1/2" ply to take that smaller radius curve, I laid it up in 2 layers of 1/4" marine plywood. I glued and screwed the first layer to the frame, and after it set up I laid the second layer on top over a generous slathering of thickened epoxy. I trimmed, sanded, and glassed it, and it's rock solid.

I had the advantage of working on the horizontal so the goop stayed where I spread it and I could use weight to hold the top layer down while it set up. Since your boat is finished and flipping it would be a big headache, you'll probably have to figure out how to do all this upside-down. Maybe work out a way to vacuum-bag it?

Paul L. on Cape Cod


--- Inbolger@yahoogroups.com, "Kendall" <ken_j_@...> wrote:
>
> I just picked up my micro navigator over the weekend...
On Mon, Oct 17, 2011 at 4:12 PM, John and Kathy Trussell
<jtrussell2@...> wrote:
>
>
>
> I would sand the existing bottom down to bare wood and epoxy another layer over it. I have heard that ¼” ply is a little light for Micro and a couple have been built with 3/8”.


Mine has a 1/4" plywood bottom and seems to work fine. Bear in mind
that the bend in the bottom panel is tight, so thicker plywood doesn't
bend as easy. And, laminating on a curve like that, well it might be
easy, but maybe not.

I would sand the existing bottom down to bare wood and epoxy another layer over it. I have heard that ¼” ply is a little light for Micro and a couple have been built with 3/8”.

 

JohnT

 

From:bolger@yahoogroups.com [mailto: bolger@yahoogroups.com ]On Behalf OfKendall
Sent:Monday, October 17, 2011 11:44 AM
To:bolger@yahoogroups.com
Subject:[bolger] Doubling a Micro Bottom

 

 

I just picked up my micro navigator over the weekend. The bottom of the boat is built to plans at 1/4" plywood and it has been patched a couple of times and is checking in places. I was wanting to get the bottom to 12" minimum or possibly 3/4" or 1" anyway. Can I epoxy some new plywood directly to the existing and then glass over that or should I remove what's there and start from scratch? The bottom is solid with out any soft spots and once I get all the paint removed I will do an inspection and replace any questionable sections if found. My reason for doubling the bottom is that I sail in a water reservoir and the level is constantly changing. It's a man made and there are lots of submerged trees that can get to just below the surface during low water periods.

I just picked up my micro navigator over the weekend. The bottom of the boat is built to plans at 1/4" plywood and it has been patched a couple of times and is checking in places. I was wanting to get the bottom to 12" minimum or possibly 3/4" or 1" anyway. Can I epoxy some new plywood directly to the existing and then glass over that or should I remove what's there and start from scratch? The bottom is solid with out any soft spots and once I get all the paint removed I will do an inspection and replace any questionable sections if found. My reason for doubling the bottom is that I sail in a water reservoir and the level is constantly changing. It's a man made and there are lots of submerged trees that can get to just below the surface during low water periods.