Squirt, Solid knee, Stem, Transom, and Breast hook?

Outboard designs up to 14'

Moderator: ttownshaw

Post Reply
Jakewilk
Posts: 1
Joined: Sat Jan 06, 2018 10:56 am

Squirt, Solid knee, Stem, Transom, and Breast hook?

Post by Jakewilk » Sat Jan 06, 2018 11:10 am

Building a Squirt is there any reason we cant substitute solid wood for plywood for the Knee, Stem, Transom, and Breast Hook? I have Ash, White Oak, Mahogany. No Marine plywood handy.

DSR
Posts: 270
Joined: Mon Mar 21, 2016 8:11 pm
Location: Allegan, Michigan

Re: Squirt, Solid knee, Stem, Transom, and Breast hook?

Post by DSR » Sat Jan 06, 2018 4:24 pm

Hi Jake,

From what I understand, the biggest reason that solid lumber isn't used for these pieces is that the lumber would have a lot of crossgrain exposed which creates weak parts that will tend to crack and fail if overstressed (especially the stem, breasthook and the knee). Plywood, just by its nature, doesn't have this issue, since the multiple layers are 90* from each other, along with the glue layers adding even more strength to the assembly, it has much greater crossgrain strength since it essentially doesn't have any exposed crossgrain. It is also more stable than solid lumber and doesn't swell and shrink nearly as much.
Another advantage is the simplicity and speed that you gain from using plywood for these pieces (just cut out the shapes and glue basically).

With that being said, you could get around this by basically "building" your own plywood from solid lumber by using multiple thinner layers epoxied together to create the thickness you need (like three 1/4" layers, with the grain oriented in different directions, to create 3/4" thickness, but it's definitely more work and you have to be really diligent about the glue-up to make sure it's done correctly. I'm actually doing something similar with those pieces in my project, for a couple different reasons.....
......and there I go rambling again......

I hope this helps Jake and you have any questions please yell. Myself and everybody else here are more than happy to help :D

Thanks,
Dave
DSR Performance - Home of yet another jet TNT build :D
Codename "Just A Little....."
viewtopic.php?f=23&t=29753

User avatar
BarnacleMike
Posts: 1043
Joined: Wed Sep 21, 2011 7:47 am
Location: North Georgia / Chattanooga Area
Contact:

Re: Squirt, Solid knee, Stem, Transom, and Breast hook?

Post by BarnacleMike » Sat Jan 06, 2018 8:24 pm

Hi Jake,

I don't see why there is any reason you couldn't use solid lumber for these pieces. After all, these things had been made of solid lumber for boats and ships for centuries before the invention of plywood. Plywood definitely has some advantages, such as providing high strength combined with light weight.

Some contemporary designers of Glen L. Witt during the 1950s, notably William Jackson, used a combination of solid stock AND plywood for these parts. Some knees and stems in his designs called for solid stock laminated in 2-to-3 inch width, then further laminated on each side with 1/4" plywood. This was partly in order to resist cracking.

To put it bluntly, both men knew what they were doing. So no, I wouldn't consider it "written in stone" that you HAVE to use plywood. I'll also add that Dave makes some really good points in advocating for marine plywood. Just carefully consider the advantages and disadvantages of either method for building these particular parts.
-Michael

"How long does it take to build a boat? Until it's finished" — yours truly

Blog (Utility & Zip): http://barnaclemikeboats.blogspot.com/
Website of Boat Photos: https://michaelsmaddox.wordpress.com

DSR
Posts: 270
Joined: Mon Mar 21, 2016 8:11 pm
Location: Allegan, Michigan

Re: Squirt, Solid knee, Stem, Transom, and Breast hook?

Post by DSR » Sun Jan 07, 2018 6:07 am

Hi guys,

Yes, I'm actually building those pieces on my TNT in solid lumber with plywood laminated to them with epoxy, along with laminating the bottom members of the frames, because of the additional stresses I'm expecting in it's intended use. Although I'm using marine plywood throughout on my project, I don't see why you couldn't use a good grade exterior ply to laminate to solid lumber for those pieces (being inside the hull and being flat pieces with no bends in the plywood), and save the marine plywood for the hull planking would be completely acceptable, and is talked about in Glens Boatbuilding With Plywood book.
DSR Performance - Home of yet another jet TNT build :D
Codename "Just A Little....."
viewtopic.php?f=23&t=29753

User avatar
Bill Edmundson
Posts: 11190
Joined: Wed Nov 23, 2005 6:45 am
Location: Birmingham, AL, USA
Contact:

Re: Squirt, Solid knee, Stem, Transom, and Breast hook?

Post by Bill Edmundson » Sun Jan 07, 2018 10:33 am

Jake

My Bartender has 3 layers of solid lumber for the stem w/staggered splices. The Tahoe stem is 2 layers of lumber and 1 layer of 3/4"ply. I see no reason that the breasthook and knees could not be built up from solid pieces.

Bill
Mini -Tug, KH Tahoe 19 & Bartender 24 - There can be no miracle recoveries without first screwing up.
Tahoe 19 Build

Hercdrvr
Posts: 719
Joined: Mon May 11, 2015 12:52 pm
Location: McKinney TX

Re: Squirt, Solid knee, Stem, Transom, and Breast hook?

Post by Hercdrvr » Sun Jan 07, 2018 11:10 am

Solid wood breasthook would be nice to screw sheer clamp into instead of the plywood endgrain. Solid wood pieces will look better than plywood for sure. Be Careful about splitting solid wood parts, especially White Oak.
Do you think you can fashion the stem out of solid wood without having a joint?
The Squirt is a great little boat. Keep us posted.
Matt B

Post Reply

Return to “Small outboards”