Lapstrake and FiberGlass

[Alixander Beck]

Has anyone tried to fiberglass a clinker built hull?

I would think that the 90 degree edges of the boards would be difficult to have the glass adhere properly to and would most likely leave dry spots.

I would be interested in hearing any methods that have worked for this, other than vaccumm bagging.

thanks

[ 10-26-2005, 02:50 PM: Message edited by: Alixander Beck ]

[mmd]

Depending on the weight of cloth, FRP needs to have between 1/8" and 1/4" radius to lie flat on a corner. Therefore, the exposed edges of the lapstrakes would have to be sanded down to these radii (the larger the better), and the inner seam of the planks would have to be filleted and sanded to a similar radius. This would be a very fussy job, but nothing compared to trying to lay in and wet out the 'glass cloth before the resin kicked off. Good luck with the project.

[RodB]

The builder of "Sally", the updated Albert Strange "Wenda" glued strips of hard wood to the edges of his glued ply lapstrake "Wenda".

Also, what about the method of glassing both sides of the the strakes before assembly...then you could glue strips of hardwood to the edges to protect the endgrain. Just some thoughts. It would be quite easy to glass in this manner.

By the way, "Sally's" builder decided that the hardwood strips were not worth the trouble, and would just triple coat the end grain with epoxy if doing it again....of course prime and paint over all. Hey Jake... how about some comments on this.

RB

[ 10-26-2005, 04:23 PM: Message edited by: RodB ]

[paladin]

round off the edges and use Xynole instead of glass....

[Canoeyawl]

I think Joel Whites method of glassing the planks before hanging is a good idea for small boats. As far as the plywood end-grain treatment, this will depend on the quality of the plywood. A hard wood strip is in order if Occume or other soft wood is the choice. I am leary of all plywood constuction excepting only the very best materials.

[Gary E]

Here we go again....LOL

MFG made some VERY nice boats like that... ALL GLASS and looked just like wood...BUY ONE !!

Ya want GLASS ? ...dont start with a dead tree

[capt jake]

Hey Jake... how about some comments on this. Huh? Who me? I can't comment on this type of construction (yet). ;)

[landlocked sailor]

Canoeyawl, I think you mean Robb White, and he only uses solid wood for his planks. Old growth tulip poplar actually. Rick

[Bill Perkins]

I've run 4 oz. glass cloth around a 1/8 th in. radius successfully . This was on the projecting edge of a 1/4 in, cabin top that was strongly curved .There was a bit of puckering ,but so slight that I didn't pick it up till I applied a white primer.The dishing was easily filled with an epoxy putty . To minimize this , I'd suggest identifying the point of greatest curvature on the plank ,and starting the wet out of the cloth there ,setting the vertical part of the weave normal to the curve of the plank . Working the cloth fore and aft from this point , the cloth can be tweaked or racked to a certain extent to bring it as near as possible to normal to the curve .

A bit of extra weight on the planking of big boats is less important .Here the Xynole Paladin recommends seems to be the thing . It holds allot of expensive , heavy resin , but drapes around difficult shapes beautifully .I was given the same recommendation by Ruel Parker ,another experienced builder .

[John Gearing]

I don't think one layer of any cloth is going to work on a lapstrake hull. Alan Vaitses (sp?) wrote in his book "Covering Boats with Fiberglass" that what you have to do is basically build a fiberglass hull on top of the wooden one. The wood will work, and one layer of cloth will tear or let go. AV sez to mechanically fasten the first layer and then add more and more layers until you have a strong glas shell. The whole idea ia a waste of time to me, however. Why do you feel you have to do this?

[Todd Bradshaw]

Other than Gary in a roundabout sort of way (and John who posted as I wrote this) I'm a bit surprised that nobody has asked what is to be gained by fiberglassing this boat, or even what it is? Fiberglass sheathing can be a very useful and durable addition in certain contexts and a worthless waste of time and money in others. If it's light enough to drape over the laps without a royal battle, it's probably not heavy enough to add much structural strength and most likely won't even stop plank movement. When that happens, it's going to fracture or delaminate and lose it's ability to keep water out. I suppose it might increase abrasion resistance slightly, but abrasion is generally not a problem on much of the hull and again, cloth light enough to drape well will only provide limited protection.

As I remember, Defender shows a method of stapling Xynole dry over a lapstrake hull (it stretches when raw) and forcing it into the laps with small battens. Then you slather it with massive amounts of epoxy (it's very thirsty cloth). Unfortunately, the fact that it can be done and that they're more than happy to show you how (and sell you the materials) doesn't automatically mean that it's a good idea or that it provides any real benefit.

In this case, it's hard to talk about products, application methods or even the potential value of doing it without knowing more about the job.

[ 10-27-2005, 01:09 AM: Message edited by: Todd Bradshaw ]

[Alixander Beck]

Thanks for the responses everyone.

There is no project that this pertains to, It was just a question I had and was curious about the pros and cons.

It sounds like a tough job, but more importantly for a lapstrake it sounds uneccessary.

thanks

[JimD]

It smells terrible however
That's because it wasn't epoxy.

[Canoeyawl]

Canoeyawl, I think you mean Robb White, and he only uses solid wood for his planks. Old growth tulip poplar actually. Rick Joel White has plans for his streched Sheerwater that specify glass over the plywood planks before hanging them. This I have seen.
Robb doesn't like plywood...

[Granville]

every time you bend a piece of glass material you are breaking fibers and weakening it. thus the more you bend and work it the weaker it will be in the final layup

[Granville]

Old growth tulip poplar where does one obtain old growth tulip poplar? and why would a non rot resistant lumber such as tulip poplar be any better in old growth vs new growth form for a boat?

[John Bell]

Tulip poplar ain't poplar. It's a relative of the magnolia family. The heartwood is reputed to be quite rot resistant.

[Canoeyawl]

“every time you bend a piece of glass material you are breaking fibers and weakening it. thus the more you bend and work it the weaker it will be in the final layup”
I’m not sure this is true, although I’m not an advocate of fiberglass, my composite wood and glass longbow has bent and worked well for over 30 years… I suspect this construction method of laying up the glass before planking would make a very stiff resilient hull.

[RodB]

All things being equal, If building a lapstrake ply hull in say a trailered 26 foot Wenda for example, I would think the added protection and stiffness offered by glassing the planks prior to assembly would be well worth it. I also would probably take the time to glue hardwood strips to the end grain or radius the edges to wrap glass or something like that.

I don't think the weight penalty for the encapsulation of the planks would be that great considering the advantages gained.

I'm sure Jake (canoe yawl) will have some comments on this to avoid wasted efforts.
RB

[Todd Bradshaw]

It would certainly add stiffness, since as soon as you go to bend the plank into place you're going to be putting a whole lot of tension on one side and a whole lot of compression on the other. I have my doubts as to whether this is really "good" for the planking as it's not a stable situation and could put a lot of sheer stress on the wood/glass bond, which really isn't all that great to start with. If you could pre-bend the plank and then glass it in that shape, it might be a different story. I have nothing against fiberglass and have used a lot of it over the years, but glassing the planks and capping plywood edges with wooden strips for a simple lapstrake boat sounds like a huge waste of time and materials to me.

The ski companies would tend to agree with Granville. They have been saying ever since the invention of fiberglass skis that every time you flex one you're breaking or stressing fibers which don't grow back and that's why skis tend to lose their camber with heavy usage. The same was always true of fiberglass whitewater kayaks. One of the most common big repair jobs for older boats was adding layers of new glass under the seats because the bottom in that area had become weakened and soft from sliding over ledges and rocks. I do believe though, that it's a serious factor only after the cloth has been saturated with resin and locked in place. I've bent raw cloth around a lot of canoe stems and never noticed any obvious weakness or ill effects as long as the yarns can move on each other and can adjust to the stress.

[ 10-27-2005, 07:39 PM: Message edited by: Todd Bradshaw ]

[Gary E]

Originally posted by Canoeyawl:
“every time you bend a piece of glass material you are breaking fibers and weakening it. thus the more you bend and work it the weaker it will be in the final layup”
I’m not sure this is true, although I’m not an advocate of fiberglass, my composite wood and glass longbow has bent and worked well for over 30 years… I suspect this construction method of laying up the glass before planking would make a very stiff resilient hull.Umm...could be...

Any material, glass in this instance in full grip on the wood, then flexed or bent and fastened to the frames etc and held in that position will contain stress and areas in tension. Just how much and wether it's acceptable is debateable. It's not like it's a steam soaked wood member that will have little stress when the steam is gone, or like a normalized steel weldment.

Your mention of a bow reminded me of the one I had, it was a recurve, made in I am guessing 1954 or 55... it eventualy delaminated in the tip area after 20 or 25 yrs... but that's only one bow... wonder how the new one are made, most likely much better and they are in the relaxed condition most of their life.

Some day, someone is gona make planks out of a "plastic" type of material, and we will be using them instead of dead trees.

[RodB]

For what its worth...I have a couple of 60" takedown hunting recurves by Mike Palmer (Sabinal, Texas), he makes one of the best laminated recurve bows in the country. I have had one of the bows strung for 5-6 years. I think it has lost maybe a couple pounds of pull weight if any. This particular bow was laminated with a strip of carbon fiber which increases the limbs accuracy...which means it stays in a more straight line when the arrow is released. I also have owned a bow of his built only with fiberglass cloth and no carbon fiber...which also was left strung for several years and has lost no power to speak of.

I think Mike pretty much comments that leaving the bows strung is harmless to the bows.

Todd, I would think the amount of tension put on the planks being bent in place would not be significant enough to cause any problems... I just don't think the bend would be severe enough to become a factor to worry about...just a hunch, but no scientific data to back up this idea.

RB

[ 10-27-2005, 08:24 PM: Message edited by: RodB ]

[Todd Bradshaw]

Try it and you'll see what I'm talking about.

[Canoeyawl]

I suspect that any boat that could be planked with out steaming would be fine using this pre-glassing technique. If steaming was required perhaps one could steam the plank, clamp it in place then remove it and glass it after it has taken a set. For example Sally (Wenda) required some steaming on a few planks aft, although no fiberglass was used these were clamped and set then removed and glued.
My recollection is that Joel specified cloth only on the outside of the planking (tension) and both sides on the bottom. I will have to recheck this now…LOL

[JimD]

I've pre-glassed panels for plywood kayaks on a couple boats. Since there are no tight bends I haven't gotten the feeling the glass or the bond to the plywood is stressed significantly at all. But when I preglassed the panels for a utility skiff with a much tighter bend at the bow there was some very minor, but visable fractures in the glass if you looked close enough. The plywood underneath seems fine.

[Todd Bradshaw]

I've been trying for two days to remember what plank-like object I pre-glassed and then tried to bend to shape and apply. Most likely it was part of a boat, but it seems to be lost somewhere in my internal hard drive. All I remember was that it fit fine before glassing, but put up a sizeable fight and made lots of unhappy noises when I tried it again after glassing. We got it in place and it worked, but it was amazingly different to handle after glassing. I did pre-glass the side panels of the wood strip drift boat that I built before bending them, but they were only glassed on their insides and the whole hull's outside was fiberglassed in one piece after the panels were assembled. It worked fine, but certainly isn't the most labor efficient way to make a four-paneled, hard-chine hull.

[ 10-28-2005, 12:55 AM: Message edited by: Todd Bradshaw ]

[JimD]

Back to the original question, I would probably still glass lapped planks, at least if it was plywood. Trying to think of a practical way to do this I might try draping the cloth over the upside down hull, wetting it out as well as possible without worrying about all those tricky tight corners at the laps but instead take a pair of sissors and cut the cloth at the laps into separate strips once the cloth was wetted and sticking to the planks. The plywood end grain I would seal up with a little silica thickened epoxy afterwards. Whadayall think?

[Todd Bradshaw]

I guess my question is "Why bother and what do you think you're really gaining?" It's not like lapstrake plywood boats are exploding all over the place due to lack of sufficient goo and fiberglass sheathing. I'd save that energy and put it into proper maintenance of the paint, varnish, etc. (or a well-made boat cover). The last lap ply boat that I worked on was an old Simmons Skiff (a real one, built by Simmons). The MDO bottom panels (not lapped) were shot from sitting out on the trailer with water in it, but the fir ply, lapped side planking was just fine with only minimal checking and nothing more protecting it than a good paint job.

[Canoeyawl]

I agree completely, it’s a waste of time… unless the plywood is junk to start with. And then the investment to glass over it would have bought you good material -LOL

[JimConlin]

I have a glued-lapstrake pulling boat that's planked with okoume. It's a lot easier to put a ding in it than in my sheathed-strip canoes.
The greater need for kid gloves is on the list of drawbacks of the construction method.
I do a lot of glass work and i don't think it's practical to glass a light lapstrake boat.

[JimD]

Here's how John Welsford does it. This is for epoxy glued plywood lapstrake, of course:

http://www.imagestation.com/picture/sraid192/p721fde0e5b7b27482f54bebdf1261daf/f1b1c7d5.jpg

The accompanying article at:

http://www.jwboatdesigns.co.nz/tips/ply/index.htm

PS - Not even wearing latex gloves! :eek:

[Frank Mehaffey]

About 6 years ago, when I was working on my 16.5 Lyman, and trying to figure out how to refresh some 40 year old 4200, I asked a respected wood boat restorer, up here in VT. He advocated putting 2-3 coats of west system, over prepared wood. By prepared, I mean dry. It sat in a dry place for a couple of months, with the original paint and primer off, down to 95% bare wood. I put 2 medium to light coats on the outside hull, three eights plywood, and put an oil primer, and 2 coats of oil enamel on top of that. Every year or two I sand down the enamel and repaint. Nothing has let go, epoxy wise, and there is no evidence of any bubbling under the epoxy. I have been very satisfied with this approach. On the inside of the hull, I lightly scraped the lapstrake joints, bow to stern, and put a very light bead of thinned epoxy into each joint.You would not know it is even there by looking.I then put varnish over the inside hull. The boat stiffened up a medium ammount, stopped leaking, and the ride is better. If I ever built a new small lapstrake, I would probably not encapsulate the whole thing, and not use the thinned epoxy inside, but I definately would do the outside of the hull. We probably have 500 hours+ of on the water time with out 48 year old since doing this, and are happy with what we did.