Re: [bolger] Re: Whalewatcher double bottom construction
Many of Phil's smaller to midsize plywood-based designs are based on multiples of standard sheet-size in either 4 or 8-foot 'rhythm.
Traditional 12:1 scarfing loses that much per sheet-length, throwing the economies off in both materials and man-power. On a 1/2 sheet you are losing 6" per sheet by turning those into saw-dust. Ergo our preference for the up-dated (power-planer-based) 'Payson Joint' in which you always get 32-feet panel-length after you joined four 8-foot lengths.
Susanne Altenburger, PB&F
----- Original Message -----From:EricSent:Friday, August 17, 2012 11:50 PMSubject:[bolger] Re: Whalewatcher double bottom constructionMy project was big enough that a gear pump would have been a good investment, except I changed epoxy companies and epoxy mixes which would have made the gear pump useless to me. A boat builder friend uses a scale effectively and that is used for the three different types of epoxies he uses. I didn't often have to do large batches of epoxy. Not having a gear pump nor scale, my method for doing big jobs was to buy paper cups of two different colors. One color for resin. One for hardener. (No thinking during the epoxy spreading rush.) I then pre measured all the epoxy I needed into the cups. When laminating my masts I had a helper mix the epoxy for me (along with a measured amount of thickener) so I could just spread. All the helper had to do was dump a hardener cup into a resin cup and mix it. The mixed epoxy was poured into a larger spreader cup into which the correct amount of thickener had been measured, and that was mixed to the proper consistency. I then traded empty spreader cup for full cup until the mast joints were coated. Then my helpers helped me get a few ties on the mast to hold it together until I could tighten hose clamps and spanish windlasses around the mast to clamp it together.
I scarf plywood together in the same manner Susan describes plus scrap wood "clamps" top and bottom of the scarf. (Plastic keeps the scrap wood clamps from becoming part of the scarf.) I have a power planer and belt sander to cut the scarfs with. They do not have to be anything like perfect. I find this to be no more trouble to do than a neatly done Payson joint. On the finished piece the joint cannot be seen after filling and sanding any imperfections in the joint.
Eric
--- Inbolger@yahoogroups.com, <philbolger@...> wrote:
>
> ...then, once you have your strong-back set up to carry the accumulating loads you get to lift the full-length 1/2-thick panel up and then over the sequence of frames and molds. You'll enjoy how that half-thick bottom drapes in a smooth non-dishing arc. You cat will 'play house' underneath in no time...
>
> Then use the pre-cut ply-pieces for the second layer to just bed them in epoxy in a 50% overlap pattern on the 'master-layer', shooting temporary dry-wall screws as you march the transverse-oriented ply-piece by piece along her length. To not have any risk of 'hard points' where the second layer just butts up against each other, you'll shoot a higher density of screws in a double-row to pull the edged smooth with each other.
>
> 6-8 hrs after you shot all these screws, you better get up at whatever indecent hour and get on with reversing that process. If you wait 12+ hours, each screw may balk at you, making you wish you'd done that job sleep-walking. If you do it in time, you get to walk all over that full-thickness bottom without sticky soles as you just pull them out in your driver's high-gear. Pulling them is always faster that shooting them.
>
> Then with thickened epoxy you'll march over it against spackling each hole with a drop. Otherwise glassing the bottom may see some of the screw-holes drool the precious stuff below. Remember that you should use hardened dry-wall screws for reliable driving in and out. And those only come in sizes 1" and longer. We found the most reliable hold with coarse-thread 1 1/4" screws for the 1" bottom lamination. Ergo holes going right through. Furthermore, any frozen drip on your bulk-heads below will have to be ground off.
>
> We found that without a go-fast (mega-cost) gear-pump we would have been in serious trouble producing a smooth lamination on bottom and our double-layer topsides. Ditto for the glassing of the bottom several times in one long session each. As a minimum you have to have an automatically-metering pump to have a second person do mostly the pumping and mixing. You'll consume a lot of the stuff running that 6'6 x 30' surface-length. Our gear-pump cost less than any serious challenge during that lamination-process in material, epoxy and man-hours would have cost. That pump is treated with great respect with the intent of having it last 'forever'...
>
> There's always more to talk about. Those two gantries came in handy many times, handy well beyond lifting and turning over the completed full-size bottom structure. Bolted together you can take them apart and pass them along, or just stow them in a modest bundle of pieces.
>
> Susanne Altenburger, PB&F
>
> ----- Original Message -----
> From: philbolger@...
> To:bolger@yahoogroups.com
> Sent: Thursday, August 16, 2012 1:51 PM
> Subject: Re: [bolger] Whalewatcher double bottom construction
>
>
>
>
> Good question.
> But first. Measure again. WHALEWATCHER is closer to 6'6" wide on her bottom.
>
> On her hull-assembly, I've just been through this last summer on the SACPAS-3 project with a Vee-nose Sharpie hull measuring 34'x7' net.
>
> I used the Payson-Joint option to assemble the first 1/2" layer of the double-layer bottom flat on the shop-floor. See MAIB Vol.29 #3 July 2011 pp.46-48 for the sequence. It requires bracing the whole assembly with temporary 2"x4" on edge to allow lifting and turning over of the floppy piece without breaking the half-joints. Then complete the joint's other side. Then lift that assembly to 90-degrees on edge and brace the piece securely in that position. We used two home-made 2x-type gantries and trailer-winches for all that large-panel handling.
>
> Check out MAIB Vol. 29 #6, p.42-43 for one way of doing your hull. And whenever you do build the strong-back, do not assume the floor is true...
>
> I could go on for hours...
>
> Susanne Altenburger, PB&F
>
> ----- Original Message -----
> From: thewildernessvoice
> To:bolger@yahoogroups.com
> Sent: Thursday, August 16, 2012 2:07 AM
> Subject: [bolger] Whalewatcher double bottom construction
>
>
>
> I have never tackled a project as big as whalewatcher before, it is almost 30'long. The bottom is doubled plywood, I am looking for ideas of support for the bottom and also a strategy for epoxy joining all the sheets. If you recommend a book i likely have it. It is 6' wide, so likely to save plywood will sue a 2ft wide strip and a 4 ft wide strip to save plywood, of course staggering the joints. I may be just over thinking this, in that I simply bevel the plywood and tape with epoxy. Going longitudinal with the plywood would allow me to use full sheets but of course with 2 ft waste and eliminate alot of taping. Then for the second layer, just epoxy and drive some screws to hold it together while it dries.
> Anyway, experience is a wonderful teacher and so for those of you who have faced this challenge and have experience, there may be something I can learn or maybe fear has caused me to over think this?
> -Jim
>
Furthermore you still need to build not just supports below for the correct curvature but you need to invest in an additional plywood layer to have an over-size base on top of which you can set up the mastic to air-seal the edges of the poly-sheet (not really a 'bag') before firing up the air-extraction compressor. And how does that vital base get its perfect curvature to serve as a reliable 'master' over which to laminate the actual hull-bottom lamination to match the topsides, frames, bulkheads ? For vacuum-bagging two hull-structural layers you thus need to build 3 layers, the first of which will never be part of the boat ?
On a flat table building your own plywood to whichever shape may be an interesting project, particularly if you dislike Payson-Joints or butt-blocks (but why would you ?). Many would just buy the stuff in adequate thickness, ply-butt or Payson-Joint the individual pieces together and get on with things. But on SACPAS-3 for instance building the 40' long topsides pieces required 2 layers of 3/8" in a curvature to match the bottom but also needed a twist over more than half the length, to eventually finish 3/4" thick, pre-curved, twisted, glassed and pre-painted to then be hung 'as is' over light-ish framing.
Where would be any time-savings with vacuum-bagging ? You sure will burn through more de facto waste you have to build first.
Unlike with the process touched upon first the other day. With the first (inside) layer of the bottom or topsides built flat on the floor joined in one piece with Payson-Joints, that layer then becomes the smoothly-draping base - supported by mostly permanent (no-waste) framing and bulkheads - over which the second plain-butted layer of 3/8" or 1/2" gets pulled over, one piece at a time, one screw at a time, in perfect control. Once screws are removed, glassing and then painting of first and second coat proceeds - all top-down ("gravity is your friend"). What remains is lifting this assembly, prep its lower edge to mate with the chine and the chine log (yes), epoxy and glass and finish that joint, add paint in respective coats, with everything then painted after all other assembly is done with 3rd and 4th coat of paint over repaired scratches and blemishes to complete the seamless structure.
Aero-space products and procedures and boat production-lines have all the opportunities and costs of elaborate initial set-up, training, and then repetition to get things to work reliably and eventually time-effectively - none of which is possible financially nor practically during a single job of doing one WHALEWATCHER, or one SACPAS-3.
In the go-fast sailing world there seems a lot of focus on avoiding hard chines and any 'signs' of using plywood at any cost; hence all the efforts at various construction-techniques allowing only certain round-bilge shapes. The oddest one may the 'Radius Chine' offering all sorts of additional work but not capitalizing on all the virtues of plywood...
In the go-fast powerboating world chines are often considered obvious dynamic and structural assets.
Yes, in the test-tank a perfectly hemispherical section is nominally often the least draggy shape. But not even the most advanced navies or civilian operators would focus on that mono-dimensional consideration as so many other functional, structural, ergonomic etc. factors are part of the overall equation for any monohull and quite a few multis as well.
Note for instance one of Phil favorite 'evolution' - at great expense of decades worth of time, energy, cost and yet to little apparent defensible reason - of how America's Cup contenders have morphed from a range of elaborate 'rigorous-since-most-efficient' round-bilge flavors to now de facto hard-chined sharpie-hulls essentially essentially copying the early 20th century 'STAR' class and elements of the later 'LIGHTNING' class. The return of four-sided de facto gaff-rigs only adds to the irony; they have seen for instance Herrershoff flavors of 1/2 a century ago with his short gaffs.... It is not inconceivable that folks will come to 'discover' the dynamic, structural, and liveaboard virtues of hard-chine shapes and structures for multi-hulls as well...
Susanne Altenburger, PB&F
----- Original Message -----From:JamesSent:Friday, August 17, 2012 10:46 PMSubject:[bolger] Re: Whalewatcher double bottom constructionI should have emphasized that I recommend using a vacuum bag to laminate the 1/2" layers, not to use 1/8" doorskins for this type of boat. Way too light....
Vacuum bagging is used in aerospace and production boat building but is not rocket science. I built a Diablo and did the side panels with two layers of doorskins vacuum bagged on a table.
JimR
--- Inbolger@yahoogroups.com, <philbolger@...> wrote:
>
> Well, as he was saying, 10:1 length-to-beam ratii seem advisable for that method.
> This dictate on hull-proportions and shapes categorically rules out anything like SACPAS-3 , WHALEWATCHER etc.. Or for that matter ready installation of just buoyancy-foam for sinking-resistance and thermal performance on liveaboards - perhaps if you go 10:1 and scour the 1" foam sheets...
>
> 2x1/2" seems more realistic in most shallow-water/beaching/grounding uses than 2x1/8"...
>
> Seems like a good idea for a very narrow slice of the spectrum of hull-shapes, and even more narrow/infinitesimal (spelling ?) for any mono-hull to take family along or just the weight of true liveaboard cruising supplies.
>
> Because of their many inherent limitations, Phil had little good to say of that and a few other construction-approaches for most types of boats, proportions, and uses he and his clients saw the need for between 1948 and 2009. For go-fast sailors he sure encouraged Newick by sending a client or two early on as Dick developed his signature approach. But most folks can't use a square foot-print thin-skinned tri that may not want to dry out.
>
> Susanne Altenburger, PB&F
>
> ----- Original Message -----
> From: James
> To:bolger@yahoogroups.com
> Sent: Friday, August 17, 2012 6:53 PM
> Subject: [bolger] Re: Whalewatcher double bottom construction
>
>
>
> Google "Cylinder Mold Kurt Hughes". Vacuum bagging would sure save some effort. I built, single handed, one of his D-30 trimarans in 1990. Granted, handling 4x8 1/8" door skins was easy compared with 1/2" Doug fir ply. Each of the 4' x 32' two-layer panels was laid up in less than two hours open time using System Three with slow hardener. This was before 9am during the summer. By late afternoon the panel was ready to demount. Two gantry cranes were made from 2x4s for the A-frame uprights and double 12' 2x6s for the beams. I had steel V-groove casters that tracked on angle iron rails on my dirt shop floor.
> JimR
>
> --- Inbolger@yahoogroups.com, "daschultz8275@" <daschultz8275@> wrote:
> >
> >
> >
> > I would plan on attaching the 1st bottom, and drill a gazillion holes in it as spots to use dry wall screws to clamp and vent the 2nd bottom. precut and dry fit the 2nd bottom, paint both surfaces w' epoxy, put on a plastic rain poncho, get underneath and start driving screws to clamp it all.
> >
> > Devlin's book on S&G building addresses this task also.
> >
> > Don
> >
>
I scarf plywood together in the same manner Susan describes plus scrap wood "clamps" top and bottom of the scarf. (Plastic keeps the scrap wood clamps from becoming part of the scarf.) I have a power planer and belt sander to cut the scarfs with. They do not have to be anything like perfect. I find this to be no more trouble to do than a neatly done Payson joint. On the finished piece the joint cannot be seen after filling and sanding any imperfections in the joint.
Eric
--- Inbolger@yahoogroups.com, <philbolger@...> wrote:
>
> ...then, once you have your strong-back set up to carry the accumulating loads you get to lift the full-length 1/2-thick panel up and then over the sequence of frames and molds. You'll enjoy how that half-thick bottom drapes in a smooth non-dishing arc. You cat will 'play house' underneath in no time...
>
> Then use the pre-cut ply-pieces for the second layer to just bed them in epoxy in a 50% overlap pattern on the 'master-layer', shooting temporary dry-wall screws as you march the transverse-oriented ply-piece by piece along her length. To not have any risk of 'hard points' where the second layer just butts up against each other, you'll shoot a higher density of screws in a double-row to pull the edged smooth with each other.
>
> 6-8 hrs after you shot all these screws, you better get up at whatever indecent hour and get on with reversing that process. If you wait 12+ hours, each screw may balk at you, making you wish you'd done that job sleep-walking. If you do it in time, you get to walk all over that full-thickness bottom without sticky soles as you just pull them out in your driver's high-gear. Pulling them is always faster that shooting them.
>
> Then with thickened epoxy you'll march over it against spackling each hole with a drop. Otherwise glassing the bottom may see some of the screw-holes drool the precious stuff below. Remember that you should use hardened dry-wall screws for reliable driving in and out. And those only come in sizes 1" and longer. We found the most reliable hold with coarse-thread 1 1/4" screws for the 1" bottom lamination. Ergo holes going right through. Furthermore, any frozen drip on your bulk-heads below will have to be ground off.
>
> We found that without a go-fast (mega-cost) gear-pump we would have been in serious trouble producing a smooth lamination on bottom and our double-layer topsides. Ditto for the glassing of the bottom several times in one long session each. As a minimum you have to have an automatically-metering pump to have a second person do mostly the pumping and mixing. You'll consume a lot of the stuff running that 6'6 x 30' surface-length. Our gear-pump cost less than any serious challenge during that lamination-process in material, epoxy and man-hours would have cost. That pump is treated with great respect with the intent of having it last 'forever'...
>
> There's always more to talk about. Those two gantries came in handy many times, handy well beyond lifting and turning over the completed full-size bottom structure. Bolted together you can take them apart and pass them along, or just stow them in a modest bundle of pieces.
>
> Susanne Altenburger, PB&F
>
> ----- Original Message -----
> From: philbolger@...
> To:bolger@yahoogroups.com
> Sent: Thursday, August 16, 2012 1:51 PM
> Subject: Re: [bolger] Whalewatcher double bottom construction
>
>
>
>
> Good question.
> But first. Measure again. WHALEWATCHER is closer to 6'6" wide on her bottom.
>
> On her hull-assembly, I've just been through this last summer on the SACPAS-3 project with a Vee-nose Sharpie hull measuring 34'x7' net.
>
> I used the Payson-Joint option to assemble the first 1/2" layer of the double-layer bottom flat on the shop-floor. See MAIB Vol.29 #3 July 2011 pp.46-48 for the sequence. It requires bracing the whole assembly with temporary 2"x4" on edge to allow lifting and turning over of the floppy piece without breaking the half-joints. Then complete the joint's other side. Then lift that assembly to 90-degrees on edge and brace the piece securely in that position. We used two home-made 2x-type gantries and trailer-winches for all that large-panel handling.
>
> Check out MAIB Vol. 29 #6, p.42-43 for one way of doing your hull. And whenever you do build the strong-back, do not assume the floor is true...
>
> I could go on for hours...
>
> Susanne Altenburger, PB&F
>
> ----- Original Message -----
> From: thewildernessvoice
> To:bolger@yahoogroups.com
> Sent: Thursday, August 16, 2012 2:07 AM
> Subject: [bolger] Whalewatcher double bottom construction
>
>
>
> I have never tackled a project as big as whalewatcher before, it is almost 30'long. The bottom is doubled plywood, I am looking for ideas of support for the bottom and also a strategy for epoxy joining all the sheets. If you recommend a book i likely have it. It is 6' wide, so likely to save plywood will sue a 2ft wide strip and a 4 ft wide strip to save plywood, of course staggering the joints. I may be just over thinking this, in that I simply bevel the plywood and tape with epoxy. Going longitudinal with the plywood would allow me to use full sheets but of course with 2 ft waste and eliminate alot of taping. Then for the second layer, just epoxy and drive some screws to hold it together while it dries.
> Anyway, experience is a wonderful teacher and so for those of you who have faced this challenge and have experience, there may be something I can learn or maybe fear has caused me to over think this?
> -Jim
>
Vacuum bagging is used in aerospace and production boat building but is not rocket science. I built a Diablo and did the side panels with two layers of doorskins vacuum bagged on a table.
JimR
--- Inbolger@yahoogroups.com, <philbolger@...> wrote:
>
> Well, as he was saying, 10:1 length-to-beam ratii seem advisable for that method.
> This dictate on hull-proportions and shapes categorically rules out anything like SACPAS-3 , WHALEWATCHER etc.. Or for that matter ready installation of just buoyancy-foam for sinking-resistance and thermal performance on liveaboards - perhaps if you go 10:1 and scour the 1" foam sheets...
>
> 2x1/2" seems more realistic in most shallow-water/beaching/grounding uses than 2x1/8"...
>
> Seems like a good idea for a very narrow slice of the spectrum of hull-shapes, and even more narrow/infinitesimal (spelling ?) for any mono-hull to take family along or just the weight of true liveaboard cruising supplies.
>
> Because of their many inherent limitations, Phil had little good to say of that and a few other construction-approaches for most types of boats, proportions, and uses he and his clients saw the need for between 1948 and 2009. For go-fast sailors he sure encouraged Newick by sending a client or two early on as Dick developed his signature approach. But most folks can't use a square foot-print thin-skinned tri that may not want to dry out.
>
> Susanne Altenburger, PB&F
>
> ----- Original Message -----
> From: James
> To:bolger@yahoogroups.com
> Sent: Friday, August 17, 2012 6:53 PM
> Subject: [bolger] Re: Whalewatcher double bottom construction
>
>
>
> Google "Cylinder Mold Kurt Hughes". Vacuum bagging would sure save some effort. I built, single handed, one of his D-30 trimarans in 1990. Granted, handling 4x8 1/8" door skins was easy compared with 1/2" Doug fir ply. Each of the 4' x 32' two-layer panels was laid up in less than two hours open time using System Three with slow hardener. This was before 9am during the summer. By late afternoon the panel was ready to demount. Two gantry cranes were made from 2x4s for the A-frame uprights and double 12' 2x6s for the beams. I had steel V-groove casters that tracked on angle iron rails on my dirt shop floor.
> JimR
>
> --- Inbolger@yahoogroups.com, "daschultz8275@" <daschultz8275@> wrote:
> >
> >
> >
> > I would plan on attaching the 1st bottom, and drill a gazillion holes in it as spots to use dry wall screws to clamp and vent the 2nd bottom. precut and dry fit the 2nd bottom, paint both surfaces w' epoxy, put on a plastic rain poncho, get underneath and start driving screws to clamp it all.
> >
> > Devlin's book on S&G building addresses this task also.
> >
> > Don
> >
>
This dictate on hull-proportions and shapes categorically rules out anything like SACPAS-3 , WHALEWATCHER etc.. Or for that matter ready installation of just buoyancy-foam for sinking-resistance and thermal performance on liveaboards - perhaps if you go 10:1 and scour the 1" foam sheets...
2x1/2" seems more realistic in most shallow-water/beaching/grounding uses than 2x1/8"...
Seems like a good idea for a very narrow slice of the spectrum of hull-shapes, and even more narrow/infinitesimal (spelling ?) for any mono-hull to take family along or just the weight of true liveaboard cruising supplies.
Because of their many inherent limitations, Phil had little good to say of that and a few other construction-approaches for most types of boats, proportions, and uses he and his clients saw the need for between 1948 and 2009. For go-fast sailors he sure encouraged Newick by sending a client or two early on as Dick developed his signature approach. But most folks can't use a square foot-print thin-skinned tri that may not want to dry out.
Susanne Altenburger, PB&F
----- Original Message -----From:JamesSent:Friday, August 17, 2012 6:53 PMSubject:[bolger] Re: Whalewatcher double bottom constructionGoogle "Cylinder Mold Kurt Hughes". Vacuum bagging would sure save some effort. I built, single handed, one of his D-30 trimarans in 1990. Granted, handling 4x8 1/8" door skins was easy compared with 1/2" Doug fir ply. Each of the 4' x 32' two-layer panels was laid up in less than two hours open time using System Three with slow hardener. This was before 9am during the summer. By late afternoon the panel was ready to demount. Two gantry cranes were made from 2x4s for the A-frame uprights and double 12' 2x6s for the beams. I had steel V-groove casters that tracked on angle iron rails on my dirt shop floor.
JimR
--- Inbolger@yahoogroups.com, "daschultz8275@..." <daschultz8275@...> wrote:
>
>
>
> I would plan on attaching the 1st bottom, and drill a gazillion holes in it as spots to use dry wall screws to clamp and vent the 2nd bottom. precut and dry fit the 2nd bottom, paint both surfaces w' epoxy, put on a plastic rain poncho, get underneath and start driving screws to clamp it all.
>
> Devlin's book on S&G building addresses this task also.
>
> Don
>
Google "Cylinder Mold Kurt Hughes". Vacuum bagging would sure save some effort. I built, single handed, one of his D-30 trimarans in 1990. Granted, handling 4x8 1/8" door skins was easy compared with 1/2" Doug fir ply. Each of the 4' x 32' two-layer panels was laid up in less than two hours open time using System Three with slow hardener. This was before 9am during the summer. By late afternoon the panel was ready to demount. Two gantry cranes were made from 2x4s for the A-frame uprights and double 12' 2x6s for the beams. I had steel V-groove casters that tracked on angle iron rails on my dirt shop floor.
JimR
--- Inbolger@yahoogroups.com, "daschultz8275@..." <daschultz8275@...> wrote:
>
>
>
> I would plan on attaching the 1st bottom, and drill a gazillion holes in it as spots to use dry wall screws to clamp and vent the 2nd bottom. precut and dry fit the 2nd bottom, paint both surfaces w' epoxy, put on a plastic rain poncho, get underneath and start driving screws to clamp it all.
>
> Devlin's book on S&G building addresses this task also.
>
> Don
>
JimR
--- Inbolger@yahoogroups.com, "daschultz8275@..." <daschultz8275@...> wrote:
>
>
>
> I would plan on attaching the 1st bottom, and drill a gazillion holes in it as spots to use dry wall screws to clamp and vent the 2nd bottom. precut and dry fit the 2nd bottom, paint both surfaces w' epoxy, put on a plastic rain poncho, get underneath and start driving screws to clamp it all.
>
> Devlin's book on S&G building addresses this task also.
>
> Don
>
Susanne Altenburger, PB&F
----- Original Message -----From:philbolger@...Sent:Friday, August 17, 2012 9:56 AMSubject:Re: [bolger] Whalewatcher double bottom construction: Screws versus Nails"Your experience may vary..."
Most if not all screw-guns have a range of clutch-settings and a few test-shots into and through the proposed wood and lamination-thickness will establish the correct setting to both drive reliably but not snap the heads. Out of many thousands of screws shot on this project, perhaps a dozen snapped (and were dug out or ground-down if in perpetually 'dry' conditions) because the clutch had not been adjusted. On this project we never lost sanding belts to screws.
We did lose them from indifference in guiding the machine, and odd accidents from (again) operator error, such as when the big BOSCH tried to eat my right jeans pant-leg; almost drew blood but only left an impressive bruise. Or when operator-error had the machine swallow its own power-cord... requiring 2-people manhandling cord and machine to reverse the process; tough cords indeed.The virtue of screws is that you have
- control over depth,
- tightness of joint,
- can shot them in near any necessary position with a long-nose drive-extension to get that bit into tight spots,
- you can change your mind as long as the epoxy has not set yet,
- you can remove them at will,
- and they are affordable.
In a production environment I'd invest in one of those specialized walking-cane length screws-gun with a belt magazine for very rapid application of selective pressure as you stand up straight and gradually walk the process over the panel-expanse.
On this particular hull-shape at least - sharpie-derivative - screws also seem superior to the infrastructure and effort necessary to setting up 'vacuum-bagging'.
But on those limited occasions that you laminate a full-length bottom-panel or topsides you indeed have to get out of bed at odd hours...
Susanne Altenburger, PB&F----- Original Message -----From:BruceHallmanSent:Thursday, August 16, 2012 7:12 PMSubject:Re: [bolger] Whalewatcher double bottom constructionDrywall screws do work. Except when the heads break off. Then you
have an expensive sanding belt consumption problem.
I agree there is a sweet spot when the screws can (usually) be removed
before the epoxy sets up hard. Except that this time frame happens
too often in the middle of the night when I would rather be sleeping.
Having tried drywall screws (and finding them useful), I still prefer
to use silicon bronze ring shank nails. They cinch up super tight.
They install just as fast (or faster) than screws, and don't eat up
the sanding belts.
Most if not all screw-guns have a range of clutch-settings and a few test-shots into and through the proposed wood and lamination-thickness will establish the correct setting to both drive reliably but not snap the heads. Out of many thousands of screws shot on this project, perhaps a dozen snapped (and were dug out or ground-down if in perpetually 'dry' conditions) because the clutch had not been adjusted. On this project we never lost sanding belts to screws.
We did lose them from indifference in guiding the machine, and odd accidents from (again) operator error, such as when the big BOSCH tried to eat my right jeans pant-leg; almost drew blood but only left an impressive bruise. Or when operator-error had the machine swallow its own power-cord... requiring 2-people manhandling cord and machine to reverse the process; tough cords indeed.
- control over depth,
- tightness of joint,
- can shot them in near any necessary position with a long-nose drive-extension to get that bit into tight spots,
- you can change your mind as long as the epoxy has not set yet,
- you can remove them at will,
- and they are affordable.
In a production environment I'd invest in one of those specialized walking-cane length screws-gun with a belt magazine for very rapid application of selective pressure as you stand up straight and gradually walk the process over the panel-expanse.
On this particular hull-shape at least - sharpie-derivative - screws also seem superior to the infrastructure and effort necessary to setting up 'vacuum-bagging'.
But on those limited occasions that you laminate a full-length bottom-panel or topsides you indeed have to get out of bed at odd hours...
Susanne Altenburger, PB&F
----- Original Message -----From:BruceHallmanSent:Thursday, August 16, 2012 7:12 PMSubject:Re: [bolger] Whalewatcher double bottom constructionDrywall screws do work. Except when the heads break off. Then you
have an expensive sanding belt consumption problem.
I agree there is a sweet spot when the screws can (usually) be removed
before the epoxy sets up hard. Except that this time frame happens
too often in the middle of the night when I would rather be sleeping.
Having tried drywall screws (and finding them useful), I still prefer
to use silicon bronze ring shank nails. They cinch up super tight.
They install just as fast (or faster) than screws, and don't eat up
the sanding belts.
I have the new instant boats book by Harold Payson where he outlines it, but will get both those issues of MAIB, because you know one nugget of info is worth the price of admission and no doubt a confirmation of a way to do things is the same.
I bought the plans through Bernie 20 odd yrs ago when Common Sense Designs was in Portland, OR.
My plan is to drift/sale this boat from the northern most point of the Colombia River (Mica creek, British Colombia) to the mouth of the Colombia (Portland, OR). I think the open house and the trailer-ability were two deciding factors. I will have 13 dams to portage. Glad to hear your still designing. Despite having these plans, I had to re think what I wanted in a sailboat for this trip. I am a minimalist at heart.
Jim
--- Inbolger@yahoogroups.com, <philbolger@...> wrote:
>
> Good question.
> But first. Measure again. WHALEWATCHER is closer to 6'6" wide on her bottom.
>
> On her hull-assembly, I've just been through this last summer on the SACPAS-3 project with a Vee-nose Sharpie hull measuring 34'x7' net.
>
> I used the Payson-Joint option to assemble the first 1/2" layer of the double-layer bottom flat on the shop-floor. See MAIB Vol.29 #3 July 2011 pp.46-48 for the sequence. It requires bracing the whole assembly with temporary 2"x4" on edge to allow lifting and turning over of the floppy piece without breaking the half-joints. Then complete the joint's other side. Then lift that assembly to 90-degrees on edge and brace the piece securely in that position. We used two home-made 2x-type gantries and trailer-winches for all that large-panel handling.
>
> Check out MAIB Vol. 29 #6, p.42-43 for one way of doing your hull. And whenever you do build the strong-back, do not assume the floor is true...
>
> I could go on for hours...
>
> Susanne Altenburger, PB&F
>
> ----- Original Message -----
> From: thewildernessvoice
> To:bolger@yahoogroups.com
> Sent: Thursday, August 16, 2012 2:07 AM
> Subject: [bolger] Whalewatcher double bottom construction
>
>
>
> I have never tackled a project as big as whalewatcher before, it is almost 30'long. The bottom is doubled plywood, I am looking for ideas of support for the bottom and also a strategy for epoxy joining all the sheets. If you recommend a book i likely have it. It is 6' wide, so likely to save plywood will sue a 2ft wide strip and a 4 ft wide strip to save plywood, of course staggering the joints. I may be just over thinking this, in that I simply bevel the plywood and tape with epoxy. Going longitudinal with the plywood would allow me to use full sheets but of course with 2 ft waste and eliminate alot of taping. Then for the second layer, just epoxy and drive some screws to hold it together while it dries.
> Anyway, experience is a wonderful teacher and so for those of you who have faced this challenge and have experience, there may be something I can learn or maybe fear has caused me to over think this?
> -Jim
>
have an expensive sanding belt consumption problem.
I agree there is a sweet spot when the screws can (usually) be removed
before the epoxy sets up hard. Except that this time frame happens
too often in the middle of the night when I would rather be sleeping.
Having tried drywall screws (and finding them useful), I still prefer
to use silicon bronze ring shank nails. They cinch up super tight.
They install just as fast (or faster) than screws, and don't eat up
the sanding belts.
Then use the pre-cut ply-pieces for the second layer to just bed them in epoxy in a 50% overlap pattern on the 'master-layer', shooting temporary dry-wall screws as you march the transverse-oriented ply-piece by piece along her length. To not have any risk of 'hard points' where the second layer just butts up against each other, you'll shoot a higher density of screws in a double-row to pull the edged smooth with each other.
6-8 hrs after you shot all these screws, you better get up at whatever indecent hour and get on with reversing that process. If you wait 12+ hours, each screw may balk at you, making you wish you'd done that job sleep-walking. If you do it in time, you get to walk all over that full-thickness bottom without sticky soles as you just pull them out in your driver's high-gear. Pulling them is always faster that shooting them.
Then with thickened epoxy you'll march over it against spackling each hole with a drop. Otherwise glassing the bottom may see some of the screw-holes drool the precious stuff below. Remember that you should use hardened dry-wall screws for reliable driving in and out. And those only come in sizes 1" and longer. We found the most reliable hold with coarse-thread 1 1/4" screws for the 1" bottom lamination. Ergo holes going right through. Furthermore, any frozen drip on your bulk-heads below will have to be ground off.
We found that without a go-fast (mega-cost) gear-pump we would have been in serious trouble producing a smooth lamination on bottom and our double-layer topsides. Ditto for the glassing of the bottom several times in one long session each. As a minimum you have to have an automatically-metering pump to have a second person do mostly the pumping and mixing. You'll consume a lot of the stuff running that 6'6 x 30' surface-length. Our gear-pump cost less than any serious challenge during that lamination-process in material, epoxy and man-hours would have cost. That pump is treated with great respect with the intent of having it last 'forever'...
There's always more to talk about. Those two gantries came in handy many times, handy well beyond lifting and turning over the completed full-size bottom structure. Bolted together you can take them apart and pass them along, or just stow them in a modest bundle of pieces.
Susanne Altenburger, PB&F
----- Original Message -----From:philbolger@...Sent:Thursday, August 16, 2012 1:51 PMSubject:Re: [bolger] Whalewatcher double bottom constructionGood question.But first. Measure again. WHALEWATCHER is closer to 6'6" wide on her bottom.
On her hull-assembly, I've just been through this last summer on the SACPAS-3 project with a Vee-nose Sharpie hull measuring 34'x7' net.
I used the Payson-Joint option to assemble the first 1/2" layer of the double-layer bottom flat on the shop-floor. See MAIB Vol.29 #3 July 2011 pp.46-48 for the sequence. It requires bracing the whole assembly with temporary 2"x4" on edge to allow lifting and turning over of the floppy piece without breaking the half-joints. Then complete the joint's other side. Then lift that assembly to 90-degrees on edge and brace the piece securely in that position. We used two home-made 2x-type gantries and trailer-winches for all that large-panel handling.
Check out MAIB Vol. 29 #6, p.42-43 for one way of doing your hull. And whenever you do build the strong-back, do not assume the floor is true...
I could go on for hours...
Susanne Altenburger, PB&F----- Original Message -----From:thewildernessvoiceSent:Thursday, August 16, 2012 2:07 AMSubject:[bolger] Whalewatcher double bottom constructionI have never tackled a project as big as whalewatcher before, it is almost 30'long. The bottom is doubled plywood, I am looking for ideas of support for the bottom and also a strategy for epoxy joining all the sheets. If you recommend a book i likely have it. It is 6' wide, so likely to save plywood will sue a 2ft wide strip and a 4 ft wide strip to save plywood, of course staggering the joints. I may be just over thinking this, in that I simply bevel the plywood and tape with epoxy. Going longitudinal with the plywood would allow me to use full sheets but of course with 2 ft waste and eliminate alot of taping. Then for the second layer, just epoxy and drive some screws to hold it together while it dries.
Anyway, experience is a wonderful teacher and so for those of you who have faced this challenge and have experience, there may be something I can learn or maybe fear has caused me to over think this?
-Jim
Devlin's book on S&G building addresses this task also.
Don
On her hull-assembly, I've just been through this last summer on the SACPAS-3 project with a Vee-nose Sharpie hull measuring 34'x7' net.
I used the Payson-Joint option to assemble the first 1/2" layer of the double-layer bottom flat on the shop-floor. See MAIB Vol.29 #3 July 2011 pp.46-48 for the sequence. It requires bracing the whole assembly with temporary 2"x4" on edge to allow lifting and turning over of the floppy piece without breaking the half-joints. Then complete the joint's other side. Then lift that assembly to 90-degrees on edge and brace the piece securely in that position. We used two home-made 2x-type gantries and trailer-winches for all that large-panel handling.
Check out MAIB Vol. 29 #6, p.42-43 for one way of doing your hull. And whenever you do build the strong-back, do not assume the floor is true...
I could go on for hours...
Susanne Altenburger, PB&F
----- Original Message -----From:thewildernessvoiceSent:Thursday, August 16, 2012 2:07 AMSubject:[bolger] Whalewatcher double bottom constructionI have never tackled a project as big as whalewatcher before, it is almost 30'long. The bottom is doubled plywood, I am looking for ideas of support for the bottom and also a strategy for epoxy joining all the sheets. If you recommend a book i likely have it. It is 6' wide, so likely to save plywood will sue a 2ft wide strip and a 4 ft wide strip to save plywood, of course staggering the joints. I may be just over thinking this, in that I simply bevel the plywood and tape with epoxy. Going longitudinal with the plywood would allow me to use full sheets but of course with 2 ft waste and eliminate alot of taping. Then for the second layer, just epoxy and drive some screws to hold it together while it dries.
Anyway, experience is a wonderful teacher and so for those of you who have faced this challenge and have experience, there may be something I can learn or maybe fear has caused me to over think this?
-Jim
<thewildernessvoice@...> wrote:
>The bottom of the Topaz which I built is also double layer plywood.
>
>
> I have never tackled a project as big as whalewatcher before, it is almost
> 30'long. The bottom is doubled plywood, I am looking for ideas of support
> for the bottom and also a strategy for epoxy joining all the sheets.
The method which I used seemed to work great. Two layers of half inch
plywood, with the 8 ft direction running across the width of the boat,
and the joints staggered 2 ft. Upside down, I built a strongback,
along the centerline of the boat with the correct bottom curvature.
Working from the bow to the stern I added one sheet at time. I mixed
epoxy and spread it on the contacting surfaces using a 10" drywall
taper's knife. (Important to sweep clean the mating surfaces with a
broom first.) Then I nailed the laminates together using silicon
bronze ringshank nails spaced at about 8" centers. To allow the
hammer in my right hand to drive the nails and not bounce I held a 3
lb maul in my left hand below as a backer. The ring shanks tightened
the assembly up perfectly snug, with zero voids. The silicon bronze
is best because it can be finished smooth with a belt sander without
eating up the sandpaper like steel nails would have done.
Anyway, experience is a wonderful teacher and so for those of you who have faced this challenge and have experience, there may be something I can learn or maybe fear has caused me to over think this?
-Jim