general questions before I build

Outboard designs up to 14'

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Robot
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general questions before I build

Postby Robot » Mon Jun 19, 2006 8:38 pm

I have 2 plywood boats. 1 is lapstrake plywood(16' thompson sea coaster) the other is mini-max like.

the lapstrake boat was built in 1956. the mini-max was built in 1962.

neither boat suffered any dry rot or damage until they were 40+ yrs old. neither boat has any fibreglass or epoxy.

the lapstrake boat had 2 6" diameter dry rot sections (1 in plywood, the other in mahogany). the mini-max still has no dry rot (44 yrs).

both were well maintained for 40 yrs (never put away wet), the mini-max was hung out to dry after each season in a hot and dry garage. the lapstrake boat sat on a trailer in the same hot and dry garage.

both boats get pettit paint every 5-10 yrs. the manageable dry rot was treated with git-rot this year, the unmanageable dry rot got replaced.

the lapstrake boat got a full resto this year (it needed it). the mini-max needed more paint.

I am planning to build a squirt this year. I have the frame kit, and I have a million simple questions that I dont believe are covered in the "boatbuilding with plywood" book and the forums.

1. do i need to encaspulate everything with epoxy? why? or just the hull?
2. I've seen some well done decks of mahog. ply, are these fibreglassed and varnished? or just varnished?
3. african mahogany or santos? I assume african.
4. stainless steel or silicon bronze? stainless steel drives better, but I've seen the horror stories regarding SS in no oxygen situations (I think i'm going to use Silicon Bronze)
5. won't a good sealer(5 coats+) and multiple coats of paint/varnish seal as well as poxy-shield and others? isn't a sealer and good paint just a good a barrier as cloth and epoxy?

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Dave Grason
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Postby Dave Grason » Mon Jun 19, 2006 9:08 pm

Ok, let's break this all down and take it one little baby step at a time. First, regarding the antique boats, if you're wanting to do restoration work on them and you have wood that has suffered damage from dry rot or regular, either one, epoxy encapsulation is not your proper course of action. You should google CPES from Smith & Company. This stuff is the right stuff for classic boat restos. But then you said the lapstrake has already gotten a full resto so just file the above info away for future reference.

The Squirt, on the other hand, is a different matter. For brand new construction and new wood, Poxy-shield is THE way to go.

1. do i need to encaspulate everything with epoxy? why? or just the hull?


A lot of different guys have different opinions here so here's mine: I'm building the Zzzip and I intend to encapsulate EVERYTHING. I know it's a lot more work but preventing rot is all about keeping moisture and air from activating the mold spores in the wood. Varnish will work for a time but full epoxy will last MUCH longer. We're talking many years with care.

2. I've seen some well done decks of mahog. ply, are these fibreglassed and varnished? or just varnished?


The best way is to epoxy encapsulate the wood. You may choose to incorporate fiberglass as well. The glass fiber cloth will give your deck toughness, abrasion resistance and some strength. The trade-off is that the grain of the wood will not be quite as distinctive looking. On my Zzzip, I plan on not using any fiberglass cloth on the deck. I DO plan on epoxying the deck and then covering it with how ever many coats of varnish are required to get my desired gloss and finish. IMO, the epoxy gives the deck the protection from water intrusion and impact resistance while the varnish gives the deck protection from UV. Hopefully, that will give me the best of both worlds.

3. african mahogany or santos? I assume african.


It's your choice. What do you like the look of? I plan on using Honduras mahogany for my deck but it's available here. In your area it may not be. However, you may be surprised to learn that many of the boat companies back in the day, didn't use the real mahogany. Their choices were as varied as could be. So there doesn't seem to be any right or wrong. As long as the wood can be protected from moisture intrusion and you like the look of it, you're good to go.

4. stainless steel or silicon bronze? stainless steel drives better, but I've seen the horror stories regarding SS in no oxygen situations (I think i'm going to use Silicon Bronze)


Silicon Bronze.

5. won't a good sealer(5 coats+) and multiple coats of paint/varnish seal as well as poxy-shield and others? isn't a sealer and good paint just a good a barrier as cloth and epoxy?


I don't believe it will protect as well. I think the Poxy-shield will do better than varnish/paint alone and unless you're planning on building a down and dirty basic boat on the smallest budget possible, spend the money on the Poxy-shield so that you won't have to worry about it. Don't go to all the trouble of hand building a fine water craft only to have water intrusion ruin all your hard work. Spend the little extra money on doing the boat right .....or as good as you can get it.

For years, I used to install, sand and finish hardwood floors. I had a definate set way that I wanted the finish to be applied. I knew that my system worked and worked really well. But folks would almost always come out to try and change everything. Everyone had their own ideas to talk about and many would ask if I'd tried such and such a product or whatever. But I always stayed with the same brand of poly, read the mixing labels and then read them again. And I did the mixing of the finish exactly according the instructions on the can. Folks would ask me to change things and I'd refuse because I knew that, for what it's worth, my system would work EVERYTIME. So I stuck with it.
Isn't it amazing!! The person that never has the fortitude to pursue his own dreams, will be the first to try and discourage you from pursuing yours.

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Robot
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Postby Robot » Sun Jul 09, 2006 10:21 pm

i am almost finished with the full resto of the 1956 thompson (lapstrake plywood).
this is the first resto of a 50 yr old boat. It has been well cared for, and save the beginning of dry-rot last year (2 ribs(white oak), and hull (marine plywood 6" rot near the transom)) this boat had never been restored or updated in any way (still running the 1957 35hp johnson javelin(like a raped ape)).

the entire restoration took 2 months of most of my spare time(about 120hrs) (i'm on varnish coat #6, so it's almost done).

this is a plywood boat(hull). the deck(mahogany plywood veneer), the transom (mahogany), the rub rails (mahogany), the ribs(white oak), the cosmetic bright work (dash/rails/chines/battens/etc)

I can't see the benefit of encapsulating wood, as you are not truly encapsulating anything, as you introduce entry points for dry rot in every screw you drive. with glass, any rot will require the replacement of the entire wood member, as the rot will be trapped.

I'll take my chances and restore my squirt in 50 years, or my kids will.

btw, my 60's minimax clone got another coat of pettit easypoxy this spring. no checking and no delamination after 40 years.

I also have a 50yr old 'ski disk' that gets a coat of paint every couple years. (this is a 4ft circle of marine plywood that is used as a starter for barefoot and old school trick-skiing(chairs/ladders/etc)).

This is not a case of "budget building", the minimal cost of fibreglass cloth is inconsequential in the life of the boat.

I am certain that a sheet of marine plywood sealed well with a quality clear sealer(multiple coats), and painted with a good marine paint(multiple coats) will last 50 years if it is allowed drying time out of the water(typical boat life). encapsulate the same disk, and rot is almost guaranteed in 20 years.

My concern is more with the lifespan of plywood that has no opportunity to 'breathe', as it's encapsulated with epoxy. It seems to me that the encapsulation method will lead to more expeditious growth of dry rot, as moisture is unable to escape. This is a typical problem in fiberglass boats built around a wood frame (most older glass boats). old sailboat builders might explain this problem better, as they all encounter it at some point (hence the west method).


whatever... you build yours, I'll build mine. Mine will be around in 50 yrs.

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Postby Amm » Mon Jul 10, 2006 8:43 am

So in other words Robot, you have experienced great success with wooden boats without epoxy encapsulation and fiberglassing. Very cool. For boats that get kiln dried each season(your hot garage is acting as a kiln) and treated very well, it may be a better way to go.

Perhaps the title of your post should have been "I want to build it the old way" instead of "General questions before I build". Dave isn't a mind reader.

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Graham Knight
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Postby Graham Knight » Mon Jul 10, 2006 10:31 am

I don't believe any of these epoxy encapsulated boats have been around long enough to give a definitive answer as to whether it's better or not, all we have at the moment is theory. And in theory it's better to encapsulate, unless you happen to believe the other theory that says it's better not to encapsulate!
I suspect what we'll find in 50 years time is that some epoxy encapsulated boats will have survived very well, and some will have rotted from the inside out, but will this be down to the method itself or to building standards and materials? That'll be a whole new argument in itself.
Having seen the way some boats are built I'll be very surprised if they last 5 years let alone 50, encapsulated or not.
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John Bowen
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Postby John Bowen » Mon Jul 10, 2006 2:04 pm

I concur Graham.
It do start with the type woods and ply one builds with and todays woods, well, it's hard to compair with yesteryears woods. Maybe that's why epoxy encapsulating came about. More so, with todays plywood.

I also agree with ya on the flight of some of the builds we've seen. But, that's OK, it's they'er choice and they'er build. Just as long that they themself, understand what they are using.
One day.

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Bill Edmundson
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Postby Bill Edmundson » Mon Jul 10, 2006 5:50 pm

I build for Me! :) If I'm going to this much trouble, I want to be proud of it! :D

But, I appreciate that others want a minimum cost boat, just to get by.

So far, my experience is, if you want to save money, go buy a used boat.

Good materials seem harder and harder to find. Or, maybe it's my memory that's harder to find. :?

The old objective was to encapsulate, they didn't have the products. Epoxy does. But, if the seal is broken the water can't get out.

Todays farmed/ fast grow woods don't have the rot resistance of old growth wood.

I've bought a lot of epoxy.

Bill
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leakcheck
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Postby leakcheck » Mon Jul 10, 2006 7:25 pm

Having seen the way some boats are built I'll be very surprised if they last 5 years let alone 50, encapsulated or not.[/quote]

Maybe that is reason alone for me not to post pictures here !!!


Steve

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Robot
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Postby Robot » Mon Jul 10, 2006 8:51 pm

I am glad that there are active responses to this forum thread.

I am passionate about craftsmanship, so my responses might seem a little abrasive. I am sorry for this.

decisions that I make while building will have positive or negative implications during the life of the boat. I would like to make the correct (positive) decisions that will extend the life of the boat as much as possible. It seems silly to put he effort into the construction to have it be a dry rotted mess in 5 years(i've seen a lot of dry rot in other boats over the years, and the majority of this has been in west system sailboat frames).

none of these decisions are financial. I am not trying to build a cheap boat. If I was, i would just buy a cheap boat.

the concept that mat'l integrity (fast growing timber) has diminished over time is an interesting one that throws another variable into the equation.

The 60's -70s glass boats havent faired to well over time. There are probably more wood boats from the previous era(40s-50s) than 60s-70s glass boats.

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Postby Scott C » Mon Jul 10, 2006 8:58 pm

Although I am a new guy on the block I also concur with the theme of building it as good as I can, from the best materials I can get. The idea that my first boat can just be 'any old thing' doesn't sit right with me, even though it is 'just' a row boat. I am still in the 'Analysis/Paralysis' stage of the game coupled with an empty wallet. However, I have purchased quality marine plywood and some associated timbers, and I will have my epoxy and glass next week. All up it will be in approximately $1500 for materials alone, but I am prepared to pay this to do the best I can.

So I also build for me (& my kids at this stage) and hopefully it will lead into bigger and better builds.
Scotty

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Robot
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Postby Robot » Mon Jul 10, 2006 9:24 pm

I'll go back to one of my origanl questions:

3. african mahogany or santos? I assume african.

or honduran,sapele, or philipine?
some of these aren't trad. mahogany, and I cant seem to find a chart that tells the whole story on all of these species. I built a 24'x24' deck of honduran mahogany(which seems to be very weather resistant(5 years of michigan winters and no warping/splitting)), and I have enough honduran left to join/plane down into reasonable decking, but I am unsure of it's resistance to dry rot. the honduran is incredibly lightweight/dry after being left to the elements. I don't know if this is a reasonable material to use for boat decking(it also dries to a yellow color, which I didnt expect). maybe this is a heartwood/sapwood problem. I do have some ipe'/ironwood. which albeit incredibly heavy, might make nice decking if i can find a bandsaw blade that will resaw it and a sander that wont burn it.

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Graham Knight
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Postby Graham Knight » Tue Jul 11, 2006 12:34 am

I've had good results with Sapele, it's reasonably priced here and quite attractive, easy to work unless you get a piece with wavy or interlocking grain, best to select your own if you can.
Khaya can be good too and is very cheap, mostly seen here as veneer up to 3mm thickness, but I know some on the forum (in the US) have found it as solid timber.
Both are quite durable and rot resistant.
I can get South American Mahogany too and that is far superior in all respects, but it's expensive and I only use it where it really counts!
Last edited by Graham Knight on Fri Jul 14, 2006 12:06 am, edited 1 time in total.
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Robot
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Postby Robot » Thu Jul 13, 2006 10:50 pm

btw. here's a buncha photos of the '56 thompson sea coaster plywood lapstrake resto.
http://smg.photobucket.com/albums/v357/ ... nuts/boat/


i'll start the squirt when I finish this. I plan to put it all back together tomorrow and be in the water on saturday

I'm in the water. I'm dealing with a ton of rotted gas/airlines. replacing all of them.


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