Re: [bolger] Pegleg Mast
Ah, that photo clarifies. So the mast snapped right at the core to core + staved transition. Now I get it. Mark's photo made that a bit unclear to me. The 20 lbs was a typo, I meant 30, that would have been the bare mast. I never weighed it all rigged. With hindsight, instead of your wedges I should have used longer staves down to the heel. I think my reason at the time was less restricted access to the bow cubby. Now I see that as a mistake. But then, where would it have failed? My guess is either ripped out the mast step or an
explosion of toothpick sized splinters.... No matter, Mark must be on the water by now. All in all, quite a life for a little quick and dirty built boat that was intended to last a year or two! Sail on.... Rick --- OnSat, 9/29/12, John Kohnen<jhkohnen@...>wrote: |
Here is a poor picture showing the original construction of Sage's mast:
http://www.boat-links.com/images/SageMastOriginal.jpg
The bottom of the partners is maybe 1/2" above the bottom of the
birdsmouth part when the mast is in place.
I put the wedges and fiberglass on after discovering that crack. I figured
the abrupt transition from the birdsmouth to the pegleg caused a stress
concentration, and that the mast bending above the partners caused the
pegleg to pry at the end of the birdsmouth part, perhaps causing the
crack. I was right about the stress concentration, because when Mark
abused the mast it broke cleanly right at the transition from the pegleg
to the birdsmouth. But you're right, Rick, the mast might never have
failed from just wind pressure. You and I both tested it good before I did
the repair. I added the wedges and fiberglass mainly to ease my mind. ;o)
Sage's mast weighs a bit over 30 lb. maybe 32 lb.? You gave me that
figure, Rick. I never weighed it. It's light for its length, but even
though you made the heel heavy, I couldn't back up far enough in the cabin
to get to the balance point. But it wasn't very hard to raise or lower
once I got the hang of it. Being able to stand inside the cabin and walk
the mast up without any risk of falling over sure was nice! :o)
You built a Good Boat, Rick. And Jim M sure designed a good one too. :o)
http://www.boat-links.com/images/SageMastOriginal.jpg
The bottom of the partners is maybe 1/2" above the bottom of the
birdsmouth part when the mast is in place.
I put the wedges and fiberglass on after discovering that crack. I figured
the abrupt transition from the birdsmouth to the pegleg caused a stress
concentration, and that the mast bending above the partners caused the
pegleg to pry at the end of the birdsmouth part, perhaps causing the
crack. I was right about the stress concentration, because when Mark
abused the mast it broke cleanly right at the transition from the pegleg
to the birdsmouth. But you're right, Rick, the mast might never have
failed from just wind pressure. You and I both tested it good before I did
the repair. I added the wedges and fiberglass mainly to ease my mind. ;o)
Sage's mast weighs a bit over 30 lb. maybe 32 lb.? You gave me that
figure, Rick. I never weighed it. It's light for its length, but even
though you made the heel heavy, I couldn't back up far enough in the cabin
to get to the balance point. But it wasn't very hard to raise or lower
once I got the hang of it. Being able to stand inside the cabin and walk
the mast up without any risk of falling over sure was nice! :o)
You built a Good Boat, Rick. And Jim M sure designed a good one too. :o)
On Sat, 29 Sep 2012 14:57:23 -0700, Rick B wrote:
> My two cents folks,
> What everyone needs to keep in mind on this repair is how the mast was
> built, where it broke and how it broke, -- at a very unusual manor and
> location.
> As the guy who built it a dozen year ago,, what I can say is;It is a
> hollow birdsmouth mast, but it is cored with solid doug fir (same plank
> as what the staves came from) from the heel to about 2 feet above the
> partners....
> Still, I seem to recall it as a very light spar (could it have been 20
> lbs naked?)
> The fiberglass banding was done by John, I'm unsure as to why? The
> vertical separation is ?? between two staves?? and how deep??? (I don't
> know). but it is above the failure area.
> ...
--
John (jkohnen@...)
The most persistent threat to freedom, to the rights of
Americans, is fear. (George Meany)
| My two cents folks, What everyone needs to keep in mind on this repair is how the mast was built, where it broke and how it broke, -- at a very unusual manor and location. As the guy who built it a dozen year ago,, what I can say is; It is a hollow birdsmouth mast, but it is cored with solid doug fir (same plank as what the staves came from) from the heel to about 2 feet above the partners. The plug was intentionally made longer than
necessary in order to weigh down the bottom of the mast so when lifting it singlehanded the base would go down and the top would go up from where you were holding it in a horizontal manor, lifting it off the birdwatcher roof while standing inside the cabin. At anchor you can only get so far from the mast step and you need the butt end to go down by gravity to raise it smoothly when bouncing around with gear scattered around your feet. Still, I seem to recall it as a very light spar (could it have been 20 lbs naked?) The fiberglass banding was done by John, I'm unsure as to why? The vertical separation is ?? between two staves?? and how deep??? (I don't know). but it is above the failure area. Why that separation came about I'm also clueless. It is hot, hot, hot and very dry, dry, dry where the spar was built and originally lived. The doug fir was also very dry .So I doubt shrinkage. Perhaps it gained moisture up north and expanded enough to separate? I don't know... Maybe a bad glue up? Was the separation close enough to the break to be part of the cause??? Moving on. Where it broke. Between the heel and the partner. NOT the usual locations, like at spreaders (none on this mast), at the end of the core (it broke much below that) or at the partners. Breaking the
solid cored section so very cleanly between the heel and partners is curious. Think of any broken hammer handle you've seen. Typically they break right at the transition where the (slightly) flexible handle enters the immovable hammer head socket, right? Not the case with this mast. Now how did it break? Mark said he snagged a small oak tree limb with the very tip of the mast while moving the boat (on the trailer?). I don't recall how fast the boat was moving, but I think Mark said something about at least a pause until suddenly it snapped. The thing must have had a huge amount of flex and the oak limb loaded up gradually as well, then it all transferred the strain to below the partner.. (I wish there was video). Interesting that none of the hollow portion of the mast, nor the end of the plug location, nor the very small section at the tip of the mast (1-1/4" diameter?), nor the repaired separation area, nor the mast partner site were the locations of the failure.. Hmmmmm, Ok, my kid the engineer points to frequency resonance oscillation transfers and stuff like that. When he recalled that the the collar at the mast partner holding the mast is solid locust for the forward half circle (meaning no give), and several rope lashings for the aft half circle (meaning some give), and that the heel is totally captive, and that the load was at the very top of the mast 19' away, with a tapered mast flexing the whole length, adding the strain gradually, and the
give of the skinny oak limb adding a gradual load as well, -- he said yup, that's how the load got transferred to below the partner.. Not something you would encounter when sailing (on water, lol). Suggested an interesting experiment. Clamp the base of a stick to an immovable object, (like the side of a leg on a heavy workench), a foot or so up lash it snugly, but with some give, then grab the top and pull it towards the direction of the lashings. See if it snaps below the lashings... Not when I tried it. Broke three at, or just above the lashings. Couldn't replicate Mark's break. I don't think the separation repair, the fiberglass banding, or the original plug had anything to do with the
failure. Good point; proves a tapered birdsmouth spar is strong, eh? Doubt it would have ever broken under sail load while floating on water. Go back to the intentional capsize pics I posted, take a look at the mast under tip load. I think the repair suggestions and concerns about banding and outerwall vs innerwall strengths etc are all irrelevant when you consider the above, regardless of the creaks John reports under sail for the mast as built and as repaired by Mark. It should do fine as is. I thing Mark has done a wonderfully creative job on this repair. Fully adequate for any
sail/wind load. I doubt any banding or sheathing were necessary. The mast isn't going to get that same load event unless Mark chooses to trailer under low hanging oak limbs of just the right height. :) :) Go sailing Mark, and give us a report, eh? Rick Bedard --- OnSat, 9/29/12, John Kohnen<jhkohnen@...>wrote: |
It may be hard to see in the photo, but the wide, single layer of
spiraled tape went more clear than where it's tripled. The main
stress is cantilevered between the partners and the step. That
allthread should take care of that - if it doesn't just push right
through the wall.
spiraled tape went more clear than where it's tripled. The main
stress is cantilevered between the partners and the step. That
allthread should take care of that - if it doesn't just push right
through the wall.
On Sep 29, 2012, at 1:16 PM, John Kohnen wrote:
> Boy! The fiberglass snapped clean right at the joint between the
> pegleg
> and the birdsmouth! I guess when I first saw photos of the break I
> thought
> you'd removed the fiberglass before taking the shot... I think I
> used two
> layers of 6 oz. cloth, just the regular stuff. Three layers of 12 oz.
> biaxial oughta work better. <g> I'm a little concerned that the three
> layers look like they're all right on top of each other at the
> joint. I
> think it'd be better to have put on a first wide layer, then a second
> narrower one, then a third one about as wide as what you did. That'd
> spread the stress transition out. Anyway, hope the fix works and
> you have
> some more fun before the monsoons start!
>
> On Sat, 29 Sep 2012 01:03:01 -0700, Mark A wrote:
>
>> ...
>> Here's how things looked after the accident. There is birdsmouth
>> fairing around the outside of the lower plug. See how the glass was
>> snapped cleanly?
>> ...
>> Just today I put the third coat on three layers of 12 oz. biaxial
>> tape, two at 45 45 straight round the joint, one spiral in between.
>> ...
>
> --
> John (jkohnen@...)
> A hypocrite is a person who -- but who isn't? (Don Marquis)
>
>
> ------------------------------------
>
> Bolger rules!!!
> - NO "GO AWAY SPAMMER!" posts!!! Please!
> - no cursing, flaming, trolling, spamming, respamming, or flogging
> dead horses
> - stay on topic, stay on thread, punctuate, no 'Ed, thanks, Fred'
> posts
> - Pls add your comments at the TOP, SIGN your posts, and snip away
> - Plans: Mr. Philip C. Bolger, P.O. Box 1209, Gloucester, MA,
> 01930, Fax: (978) 282-1349
> - Unsubscribe:bolger-unsubscribe@yahoogroups.com
> - Open discussion:bolger_coffee_lounge-subscribe@yahoogroups.com
> Yahoo! Groups Links
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>
>
Boy! The fiberglass snapped clean right at the joint between the pegleg
and the birdsmouth! I guess when I first saw photos of the break I thought
you'd removed the fiberglass before taking the shot... I think I used two
layers of 6 oz. cloth, just the regular stuff. Three layers of 12 oz.
biaxial oughta work better. <g> I'm a little concerned that the three
layers look like they're all right on top of each other at the joint. I
think it'd be better to have put on a first wide layer, then a second
narrower one, then a third one about as wide as what you did. That'd
spread the stress transition out. Anyway, hope the fix works and you have
some more fun before the monsoons start!
and the birdsmouth! I guess when I first saw photos of the break I thought
you'd removed the fiberglass before taking the shot... I think I used two
layers of 6 oz. cloth, just the regular stuff. Three layers of 12 oz.
biaxial oughta work better. <g> I'm a little concerned that the three
layers look like they're all right on top of each other at the joint. I
think it'd be better to have put on a first wide layer, then a second
narrower one, then a third one about as wide as what you did. That'd
spread the stress transition out. Anyway, hope the fix works and you have
some more fun before the monsoons start!
On Sat, 29 Sep 2012 01:03:01 -0700, Mark A wrote:
> ...
> Here's how things looked after the accident. There is birdsmouth
> fairing around the outside of the lower plug. See how the glass was
> snapped cleanly?
> ...
> Just today I put the third coat on three layers of 12 oz. biaxial
> tape, two at 45 45 straight round the joint, one spiral in between.
> ...
--
John (jkohnen@...)
A hypocrite is a person who -- but who isn't? (Don Marquis)
All good ideas here. I did use epoxy and heavy biaxial tape.. The splice is just below the partners, so has to do no bending. The BW slot top with mast coming up through it, the placement of the mast at the forward bulkhead, and the present nicely fitted fabric cover were not conducive to the tabernacle idea, much as I like it.
I think the tape does the duty of what you call the "caps", spanning the joint well.
We'll see if theory works as well as practice...
Mark
On Sep 29, 2012, at 12:28 PM, steve statkus wrote:
The joint between your fiberglass and wood is in shear as the mast bends. Think of an I-beam in bending. The upper surface is in tension/shear, the lower surface in compression. The neutral point, (where your all thread is) has almost zero load. If you used polyester resin and regular fiberglass cloth you probably did not get any resin down in to the pores of the wood. You might want to check out West Epoxy for their products. Consider some type of cap strips spanning the joint that act like the caps on I-beams. Or, thinking outside the box, could you make the mast into a folding mast with tabernacle?
Steve......the splice guy
You can't leave epoxy with out UV protection. Degrades in a couple of years.
HJ
HJ
On 9/29/2012 5:03 AM, Douglas Pollard wrote:
> I am setting here thinking through my probably flawed logic. It has
> always been my understanding that solid mast is not as strong as a
> larger one that is hollow. The thing being that they both weigh the
> same. Mr. Bolger told me that the mast compliments the lift on the sail
> by improving the shape of the sails leading edge. This may be true If
> you are using his figure eight lacing that allows the sail to revolve
> around the mast. So up to a point maybe the bigger diameter mast might
> be more efficient??? Epoxy and glass on the outside may well strengthen
> the mast if the weather is cool?? Epoxy softens in heat so I would not
> varnish the mast I would paint it white to reflect sunlight at least in
> the area of the splice. I built a mast for a 35 ft sail boat about 40
> years ago. It was rectangular in shape and I built it hollow from bottom
> to top with drip proof vents at the top and hollow all the way to the
> bottom so that air would be able to circulate up through it. I saw the
> boat a few years ago and she had been through several owners but still
> carried the same mast. I believe that fiberglassing a wooden mast is a
> mistake. I think a slightly larger mast that weighs the same as the
> fiberglassed one is stronger. All this is mostly my thinking and I am
> posting it only as speculation and food for thought. Doug
>
> On 09/29/2012 04:03 AM, Mark Albanese wrote:
>>
>>
>>
>
>
> ------------------------------------
>
> Bolger rules!!!
> - NO "GO AWAY SPAMMER!" posts!!! Please!
> - no cursing, flaming, trolling, spamming, respamming, or flogging dead horses
> - stay on topic, stay on thread, punctuate, no 'Ed, thanks, Fred' posts
> - Pls add your comments at the TOP, SIGN your posts, and snip away
> - Plans: Mr. Philip C. Bolger, P.O. Box 1209, Gloucester, MA, 01930, Fax: (978) 282-1349
> - Unsubscribe:bolger-unsubscribe@yahoogroups.com
> - Open discussion:bolger_coffee_lounge-subscribe@yahoogroups.comYahoo! Groups Links
>
>
>
>
The joint between your fiberglass and wood is in shear as the mast bends. Think of an I-beam in bending. The upper surface is in tension/shear, the lower surface in compression. The neutral point, (where your all thread is) has almost zero load. If you used polyester resin and regular fiberglass cloth you probably did not get any resin down in to the pores of the wood. You might want to check out West Epoxy for their products. Consider some type of cap strips spanning the joint that act like the caps on I-beams. Or, thinking outside the box, could you make the mast into a folding mast with tabernacle?
Steve......the splice guy
Steve......the splice guy
On Sat, Sep 29, 2012 at 11:14 AM, Eric<eric14850@...>wrote:I concur. With regard to fiberglass on a mast, epoxy fiberglass has less elasticity than the wood. Theoretically, if it is on the outside of a mast it will take most of the strain until the fiberglass fails. Fiberglassing the inside makes more sense from an engineering point of view (there is less movement on the inside of the mast). Doug may be correct that the weight to strength ratio compared to all wood may not be good. I epoxy fiberglassed the inside of my masts to prevent rot and perhaps add some strength. If I had read what Doug had to say before building my masts I would not have done so. Nothing like experience to point out the proper direction.
Eric
--- Inbolger@yahoogroups.com, Douglas Pollard <dougpol1@...> wrote:
>
> I am setting here thinking through my probably flawed logic. It has
> always been my understanding that solid mast is not as strong as a
> larger one that is hollow. The thing being that they both weigh the
> same. Mr. Bolger told me that the mast compliments the lift on the sail
> by improving the shape of the sails leading edge. This may be true If
> you are using his figure eight lacing that allows the sail to revolve
> around the mast. So up to a point maybe the bigger diameter mast might
> be more efficient??? Epoxy and glass on the outside may well strengthen
> the mast if the weather is cool?? Epoxy softens in heat so I would not
> varnish the mast I would paint it white to reflect sunlight at least in
> the area of the splice. I built a mast for a 35 ft sail boat about 40
> years ago. It was rectangular in shape and I built it hollow from bottom
> to top with drip proof vents at the top and hollow all the way to the
> bottom so that air would be able to circulate up through it. I saw the
> boat a few years ago and she had been through several owners but still
> carried the same mast. I believe that fiberglassing a wooden mast is a
> mistake. I think a slightly larger mast that weighs the same as the
> fiberglassed one is stronger. All this is mostly my thinking and I am
> posting it only as speculation and food for thought. Doug
>
> On 09/29/2012 04:03 AM, Mark Albanese wrote:
> >
> >
> > Thanks for the encouragement, John. With so many steps I had to do it in
> > 6 ounce dribs and drabs, so it took awhile to get this far. Still, much
> > easier than building another one. And Rick did some very nice work worth
> > saving. Light it is. Except for this flaw, solid. Nice fittings. I love
> > its beautiful built in curve.
> >
> >
> > Here's how things looked after the accident. There is birdsmouth fairing
> > around the outside of the lower plug. See how the glass was snapped cleanly?
> >
> > **
> >
> > The original crack between the strakes is just above this break and must
> > have been a quarter inch wide and six inches long before It stabilized
> > with the T88. No new damage there.
> >
> >
> > I cleaned up the shards, filled flush with a silica and epoxy, then
> > drilled stepped holes for a foot long piece of 3/4" zinc plated
> > all-thread. I'd thought 12" just right, long enough to reach into the
> > thick part of the foot, spanning the joint strongly, and not going so
> > far up as to create a perfect spot to snap just above the partners. Not
> > to mention 6" either way was about all I thought to get reliably straight.
> >
> >
> >
> >
> > The original idea was to create nice threads in both the upper and lower
> > sections and then screw them together, mating the faces carefully with
> > thick epoxy. I vaselined the metal in this first try, but hey it was
> > stuck for good. In the end I just stuffed as much not too thick and not
> > too thin epoxy down the hole as possible and stuck 'em together. Just
> > enough oozed out to make a good join.
> >
> >
> >
> > Here, ready for glassing.
> >
> >
> >
> > Just today I put the third coat on three layers of 12 oz. biaxial tape,
> > two at 45 45 straight round the joint, one spiral in between.
> >
> > It's the first time I've used this and like it rather more than the
> > selvage edge material. The edges will need less grinding off and they
> > don't unravel nearly as much as plain fabric. It doesn't go as clear as
> > looser fabric. No matter; maybe add a bright white racing stripe.
> >
> > This photo is of the drying second coat. At half 85 degrees; half 50
> > over night ( ah, Portland late summer), it needs some cleaning up on
> > Sunday morning and waiting till late next week for the Raka to mostly
> > harden.
> >
> >
> >
> >
> > Then it's off to give it a try with anemometer in hand. Whoopee!
> > Mark
> >
> >
> >
> >> On Sep 28, 2012, at 10:56 PM, John Kohnen wrote:
> >>
> >>> "Dime?" "Nickel?" I guess the tale is growing with the telling. ;o)
> >>>
> >>> Most of the stress on a mast is handled by the material near the
> >>> _outside_
> >>> of the mast. Your all-thread solution is a good one for holding the two
> >>> parts of Sage's mast together and in line, Mark, but put plenty of
> >>> 'glass
> >>> on the outside of the mast to carry the load. And make sure you've
> >>> sanded
> >>> all the varnish away before you do it. <g>
> >>>
>
My father made a mast for the 42ft sharpie my family had when I was a
boy. It was hollow and it had a plug in it to a few feet above the
partners. He cut the upper end of the plug on a long 30 degree angle
and the lowest side of it had a 1 inch slot cut in it to let any water
run out the bottom. The inside had been coated with a mixture of
varnish and
diluted pine tar. We poured more in through the slot at the bottom
raised and lowered each end of the mast and rotated it at the same time
so that there would be no uncovered wood in any corner. The mast was
glued up with casein glue I think the brand name was Casamite It was
thought to be very strong and a little more forgiving in fitting. The
boat originally had a solid mast and I think my father was trying to get
one up on some of the neighbors who had sharpies. When the boats were
out fishing there was always a race home and a lot of chatter and
teasing went on when we all got in the creek. A little speed was big
bragging rights.
All the boats had free standing masts so that at a mooring when
the sails were drying the boom could not get up against shrouds. The
sails being canvas they had to be set flying the next day after sailing
as mildew was deadly to canvas and sunlight is deadly to mildew.
Doug
boy. It was hollow and it had a plug in it to a few feet above the
partners. He cut the upper end of the plug on a long 30 degree angle
and the lowest side of it had a 1 inch slot cut in it to let any water
run out the bottom. The inside had been coated with a mixture of
varnish and
diluted pine tar. We poured more in through the slot at the bottom
raised and lowered each end of the mast and rotated it at the same time
so that there would be no uncovered wood in any corner. The mast was
glued up with casein glue I think the brand name was Casamite It was
thought to be very strong and a little more forgiving in fitting. The
boat originally had a solid mast and I think my father was trying to get
one up on some of the neighbors who had sharpies. When the boats were
out fishing there was always a race home and a lot of chatter and
teasing went on when we all got in the creek. A little speed was big
bragging rights.
All the boats had free standing masts so that at a mooring when
the sails were drying the boom could not get up against shrouds. The
sails being canvas they had to be set flying the next day after sailing
as mildew was deadly to canvas and sunlight is deadly to mildew.
Doug
On 09/29/2012 11:14 AM, Eric wrote:
> I concur. With regard to fiberglass on a mast, epoxy fiberglass has less
> elasticity than the wood. Theoretically, if it is on the outside of a
> mast it will take most of the strain until the fiberglass fails.
> Fiberglassing the inside makes more sense from an engineering point of
> view (there is less movement on the inside of the mast). Doug may be
> correct that the weight to strength ratio compared to all wood may not
> be good. I epoxy fiberglassed the inside of my masts to prevent rot and
> perhaps add some strength. If I had read what Doug had to say before
> building my masts I would not have done so. Nothing like experience to
> point out the proper direction.
>
> Eric
>
> --- Inbolger@yahoogroups.com<mailto:bolger%40yahoogroups.com>, Douglas
> Pollard <dougpol1@...> wrote:
> >
> > I am setting here thinking through my probably flawed logic. It has
> > always been my understanding that solid mast is not as strong as a
> > larger one that is hollow. The thing being that they both weigh the
> > same. Mr. Bolger told me that the mast compliments the lift on the sail
> > by improving the shape of the sails leading edge. This may be true If
> > you are using his figure eight lacing that allows the sail to revolve
> > around the mast. So up to a point maybe the bigger diameter mast might
> > be more efficient??? Epoxy and glass on the outside may well strengthen
> > the mast if the weather is cool?? Epoxy softens in heat so I would not
> > varnish the mast I would paint it white to reflect sunlight at least in
> > the area of the splice. I built a mast for a 35 ft sail boat about 40
> > years ago. It was rectangular in shape and I built it hollow from bottom
> > to top with drip proof vents at the top and hollow all the way to the
> > bottom so that air would be able to circulate up through it. I saw the
> > boat a few years ago and she had been through several owners but still
> > carried the same mast. I believe that fiberglassing a wooden mast is a
> > mistake. I think a slightly larger mast that weighs the same as the
> > fiberglassed one is stronger. All this is mostly my thinking and I am
> > posting it only as speculation and food for thought. Doug
> >
> > On 09/29/2012 04:03 AM, Mark Albanese wrote:
> > >
> > >
> > > Thanks for the encouragement, John. With so many steps I had to do
> it in
> > > 6 ounce dribs and drabs, so it took awhile to get this far. Still, much
> > > easier than building another one. And Rick did some very nice work
> worth
> > > saving. Light it is. Except for this flaw, solid. Nice fittings. I love
> > > its beautiful built in curve.
> > >
> > >
> > > Here's how things looked after the accident. There is birdsmouth
> fairing
> > > around the outside of the lower plug. See how the glass was snapped
> cleanly?
> > >
> > > **
> > >
> > > The original crack between the strakes is just above this break and
> must
> > > have been a quarter inch wide and six inches long before It stabilized
> > > with the T88. No new damage there.
> > >
> > >
> > > I cleaned up the shards, filled flush with a silica and epoxy, then
> > > drilled stepped holes for a foot long piece of 3/4" zinc plated
> > > all-thread. I'd thought 12" just right, long enough to reach into the
> > > thick part of the foot, spanning the joint strongly, and not going so
> > > far up as to create a perfect spot to snap just above the partners. Not
> > > to mention 6" either way was about all I thought to get reliably
> straight.
> > >
> > >
> > >
> > >
> > > The original idea was to create nice threads in both the upper and
> lower
> > > sections and then screw them together, mating the faces carefully with
> > > thick epoxy. I vaselined the metal in this first try, but hey it was
> > > stuck for good. In the end I just stuffed as much not too thick and not
> > > too thin epoxy down the hole as possible and stuck 'em together. Just
> > > enough oozed out to make a good join.
> > >
> > >
> > >
> > > Here, ready for glassing.
> > >
> > >
> > >
> > > Just today I put the third coat on three layers of 12 oz. biaxial tape,
> > > two at 45 45 straight round the joint, one spiral in between.
> > >
> > > It's the first time I've used this and like it rather more than the
> > > selvage edge material. The edges will need less grinding off and they
> > > don't unravel nearly as much as plain fabric. It doesn't go as clear as
> > > looser fabric. No matter; maybe add a bright white racing stripe.
> > >
> > > This photo is of the drying second coat. At half 85 degrees; half 50
> > > over night ( ah, Portland late summer), it needs some cleaning up on
> > > Sunday morning and waiting till late next week for the Raka to mostly
> > > harden.
> > >
> > >
> > >
> > >
> > > Then it's off to give it a try with anemometer in hand. Whoopee!
> > > Mark
> > >
> > >
> > >
> > >> On Sep 28, 2012, at 10:56 PM, John Kohnen wrote:
> > >>
> > >>> "Dime?" "Nickel?" I guess the tale is growing with the telling. ;o)
> > >>>
> > >>> Most of the stress on a mast is handled by the material near the
> > >>> _outside_
> > >>> of the mast. Your all-thread solution is a good one for holding
> the two
> > >>> parts of Sage's mast together and in line, Mark, but put plenty of
> > >>> 'glass
> > >>> on the outside of the mast to carry the load. And make sure you've
> > >>> sanded
> > >>> all the varnish away before you do it. <g>
> > >>>
> >
>
>
I concur. With regard to fiberglass on a mast, epoxy fiberglass has less elasticity than the wood. Theoretically, if it is on the outside of a mast it will take most of the strain until the fiberglass fails. Fiberglassing the inside makes more sense from an engineering point of view (there is less movement on the inside of the mast). Doug may be correct that the weight to strength ratio compared to all wood may not be good. I epoxy fiberglassed the inside of my masts to prevent rot and perhaps add some strength. If I had read what Doug had to say before building my masts I would not have done so. Nothing like experience to point out the proper direction.
Eric
Eric
--- Inbolger@yahoogroups.com, Douglas Pollard <dougpol1@...> wrote:
>
> I am setting here thinking through my probably flawed logic. It has
> always been my understanding that solid mast is not as strong as a
> larger one that is hollow. The thing being that they both weigh the
> same. Mr. Bolger told me that the mast compliments the lift on the sail
> by improving the shape of the sails leading edge. This may be true If
> you are using his figure eight lacing that allows the sail to revolve
> around the mast. So up to a point maybe the bigger diameter mast might
> be more efficient??? Epoxy and glass on the outside may well strengthen
> the mast if the weather is cool?? Epoxy softens in heat so I would not
> varnish the mast I would paint it white to reflect sunlight at least in
> the area of the splice. I built a mast for a 35 ft sail boat about 40
> years ago. It was rectangular in shape and I built it hollow from bottom
> to top with drip proof vents at the top and hollow all the way to the
> bottom so that air would be able to circulate up through it. I saw the
> boat a few years ago and she had been through several owners but still
> carried the same mast. I believe that fiberglassing a wooden mast is a
> mistake. I think a slightly larger mast that weighs the same as the
> fiberglassed one is stronger. All this is mostly my thinking and I am
> posting it only as speculation and food for thought. Doug
>
> On 09/29/2012 04:03 AM, Mark Albanese wrote:
> >
> >
> > Thanks for the encouragement, John. With so many steps I had to do it in
> > 6 ounce dribs and drabs, so it took awhile to get this far. Still, much
> > easier than building another one. And Rick did some very nice work worth
> > saving. Light it is. Except for this flaw, solid. Nice fittings. I love
> > its beautiful built in curve.
> >
> >
> > Here's how things looked after the accident. There is birdsmouth fairing
> > around the outside of the lower plug. See how the glass was snapped cleanly?
> >
> > **
> >
> > The original crack between the strakes is just above this break and must
> > have been a quarter inch wide and six inches long before It stabilized
> > with the T88. No new damage there.
> >
> >
> > I cleaned up the shards, filled flush with a silica and epoxy, then
> > drilled stepped holes for a foot long piece of 3/4" zinc plated
> > all-thread. I'd thought 12" just right, long enough to reach into the
> > thick part of the foot, spanning the joint strongly, and not going so
> > far up as to create a perfect spot to snap just above the partners. Not
> > to mention 6" either way was about all I thought to get reliably straight.
> >
> >
> >
> >
> > The original idea was to create nice threads in both the upper and lower
> > sections and then screw them together, mating the faces carefully with
> > thick epoxy. I vaselined the metal in this first try, but hey it was
> > stuck for good. In the end I just stuffed as much not too thick and not
> > too thin epoxy down the hole as possible and stuck 'em together. Just
> > enough oozed out to make a good join.
> >
> >
> >
> > Here, ready for glassing.
> >
> >
> >
> > Just today I put the third coat on three layers of 12 oz. biaxial tape,
> > two at 45 45 straight round the joint, one spiral in between.
> >
> > It's the first time I've used this and like it rather more than the
> > selvage edge material. The edges will need less grinding off and they
> > don't unravel nearly as much as plain fabric. It doesn't go as clear as
> > looser fabric. No matter; maybe add a bright white racing stripe.
> >
> > This photo is of the drying second coat. At half 85 degrees; half 50
> > over night ( ah, Portland late summer), it needs some cleaning up on
> > Sunday morning and waiting till late next week for the Raka to mostly
> > harden.
> >
> >
> >
> >
> > Then it's off to give it a try with anemometer in hand. Whoopee!
> > Mark
> >
> >
> >
> >> On Sep 28, 2012, at 10:56 PM, John Kohnen wrote:
> >>
> >>> "Dime?" "Nickel?" I guess the tale is growing with the telling. ;o)
> >>>
> >>> Most of the stress on a mast is handled by the material near the
> >>> _outside_
> >>> of the mast. Your all-thread solution is a good one for holding the two
> >>> parts of Sage's mast together and in line, Mark, but put plenty of
> >>> 'glass
> >>> on the outside of the mast to carry the load. And make sure you've
> >>> sanded
> >>> all the varnish away before you do it. <g>
> >>>
>
I am setting here thinking through my probably flawed logic. It has
always been my understanding that solid mast is not as strong as a
larger one that is hollow. The thing being that they both weigh the
same. Mr. Bolger told me that the mast compliments the lift on the sail
by improving the shape of the sails leading edge. This may be true If
you are using his figure eight lacing that allows the sail to revolve
around the mast. So up to a point maybe the bigger diameter mast might
be more efficient??? Epoxy and glass on the outside may well strengthen
the mast if the weather is cool?? Epoxy softens in heat so I would not
varnish the mast I would paint it white to reflect sunlight at least in
the area of the splice. I built a mast for a 35 ft sail boat about 40
years ago. It was rectangular in shape and I built it hollow from bottom
to top with drip proof vents at the top and hollow all the way to the
bottom so that air would be able to circulate up through it. I saw the
boat a few years ago and she had been through several owners but still
carried the same mast. I believe that fiberglassing a wooden mast is a
mistake. I think a slightly larger mast that weighs the same as the
fiberglassed one is stronger. All this is mostly my thinking and I am
posting it only as speculation and food for thought. Doug
always been my understanding that solid mast is not as strong as a
larger one that is hollow. The thing being that they both weigh the
same. Mr. Bolger told me that the mast compliments the lift on the sail
by improving the shape of the sails leading edge. This may be true If
you are using his figure eight lacing that allows the sail to revolve
around the mast. So up to a point maybe the bigger diameter mast might
be more efficient??? Epoxy and glass on the outside may well strengthen
the mast if the weather is cool?? Epoxy softens in heat so I would not
varnish the mast I would paint it white to reflect sunlight at least in
the area of the splice. I built a mast for a 35 ft sail boat about 40
years ago. It was rectangular in shape and I built it hollow from bottom
to top with drip proof vents at the top and hollow all the way to the
bottom so that air would be able to circulate up through it. I saw the
boat a few years ago and she had been through several owners but still
carried the same mast. I believe that fiberglassing a wooden mast is a
mistake. I think a slightly larger mast that weighs the same as the
fiberglassed one is stronger. All this is mostly my thinking and I am
posting it only as speculation and food for thought. Doug
On 09/29/2012 04:03 AM, Mark Albanese wrote:
>
>
> Thanks for the encouragement, John. With so many steps I had to do it in
> 6 ounce dribs and drabs, so it took awhile to get this far. Still, much
> easier than building another one. And Rick did some very nice work worth
> saving. Light it is. Except for this flaw, solid. Nice fittings. I love
> its beautiful built in curve.
>
>
> Here's how things looked after the accident. There is birdsmouth fairing
> around the outside of the lower plug. See how the glass was snapped cleanly?
>
> **
>
> The original crack between the strakes is just above this break and must
> have been a quarter inch wide and six inches long before It stabilized
> with the T88. No new damage there.
>
>
> I cleaned up the shards, filled flush with a silica and epoxy, then
> drilled stepped holes for a foot long piece of 3/4" zinc plated
> all-thread. I'd thought 12" just right, long enough to reach into the
> thick part of the foot, spanning the joint strongly, and not going so
> far up as to create a perfect spot to snap just above the partners. Not
> to mention 6" either way was about all I thought to get reliably straight.
>
>
>
>
> The original idea was to create nice threads in both the upper and lower
> sections and then screw them together, mating the faces carefully with
> thick epoxy. I vaselined the metal in this first try, but hey it was
> stuck for good. In the end I just stuffed as much not too thick and not
> too thin epoxy down the hole as possible and stuck 'em together. Just
> enough oozed out to make a good join.
>
>
>
> Here, ready for glassing.
>
>
>
> Just today I put the third coat on three layers of 12 oz. biaxial tape,
> two at 45 45 straight round the joint, one spiral in between.
>
> It's the first time I've used this and like it rather more than the
> selvage edge material. The edges will need less grinding off and they
> don't unravel nearly as much as plain fabric. It doesn't go as clear as
> looser fabric. No matter; maybe add a bright white racing stripe.
>
> This photo is of the drying second coat. At half 85 degrees; half 50
> over night ( ah, Portland late summer), it needs some cleaning up on
> Sunday morning and waiting till late next week for the Raka to mostly
> harden.
>
>
>
>
> Then it's off to give it a try with anemometer in hand. Whoopee!
> Mark
>
>
>
>> On Sep 28, 2012, at 10:56 PM, John Kohnen wrote:
>>
>>> "Dime?" "Nickel?" I guess the tale is growing with the telling. ;o)
>>>
>>> Most of the stress on a mast is handled by the material near the
>>> _outside_
>>> of the mast. Your all-thread solution is a good one for holding the two
>>> parts of Sage's mast together and in line, Mark, but put plenty of
>>> 'glass
>>> on the outside of the mast to carry the load. And make sure you've
>>> sanded
>>> all the varnish away before you do it. <g>
>>>
Thanks for the encouragement, John. With so many steps I had to do it in 6 ounce dribs and drabs, so it took awhile to get this far. Still, much easier than building another one. And Rick did some very nice work worth saving. Light it is. Except for this flaw, solid. Nice fittings. I love its beautiful built in curve.
Here's how things looked after the accident. There is birdsmouth fairing around the outside of the lower plug. See how the glass was snapped cleanly?
The original crack between the strakes is just above this break and must have been a quarter inch wide and six inches long before It stabilized with the T88. No new damage there.
I cleaned up the shards, filled flush with a silica and epoxy, then drilled stepped holes for a foot long piece of 3/4" zinc plated all-thread. I'd thought 12" just right, long enough to reach into the thick part of the foot, spanning the joint strongly, and not going so far up as to create a perfect spot to snap just above the partners. Not to mention 6" either way was about all I thought to get reliablystraight.
The original idea was to create nice threads in both the upper and lower sections and then screw them together, mating the faces carefully with thick epoxy. I vaselined the metal in this first try, but hey it was stuck for good. In the end I just stuffed as much not too thick and not too thin epoxy down the hole as possible and stuck 'em together. Just enough oozed out to make a good join.
Here, ready for glassing.
Just today I put the third coat on three layers of 12 oz. biaxial tape, two at 45 45 straight round the joint, one spiral in between.
It's the first time I've used this and like it rather more than the selvage edge material. The edges will need less grinding off and they don't unravel nearly as much as plain fabric. It doesn't go as clear as looser fabric. No matter; maybe add a bright white racing stripe.
This photo is of the drying second coat. At half 85 degrees; half 50 over night ( ah, Portland late summer), it needs some cleaning up on Sunday morning and waiting till late next week for the Raka to mostly harden.
Then it's off to give it a try with anemometer in hand. Whoopee!
Mark
On Sep 28, 2012, at 10:56 PM, John Kohnen wrote:"Dime?" "Nickel?" I guess the tale is growing with the telling. ;o)Most of the stress on a mast is handled by the material near the _outside_of the mast. Your all-thread solution is a good one for holding the twoparts of Sage's mast together and in line, Mark, but put plenty of 'glasson the outside of the mast to carry the load. And make sure you've sandedall the varnish away before you do it. <g>