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Varnished vs. oiled

Posted by ozarkdrifter 
Varnished vs. oiled
September 27, 2019 02:47AM
An old conversation I'm sure, but one I wanted to get some clarification on as I begin to order supplies. In an effort to have the most functional, least maintenance boat I could build that was still a little on the "fancy wooden boat" side of things I decided to set up as follows:

Painted exterior/interior side panels. Leave gunwales and a few internal components such as casting braces, seat frames, side tray tops, etc as raw ash / meranti plywood and oil with some version or another of "boat sauce." Bottom coating conversation for another day.

I know many builders glass the gunwales and I'm certain this adds to the overall stiffness of the boat, increasing performance. My question is by skipping this step will I be missing out on much or will it be just fine? Also if there are unforeseen consequences to this approach, would be good to find out sooner rather than later! Appreciate any insights.

Brad
Re: Varnished vs. oiled
September 27, 2019 12:12PM
Be just fine. There are 50 year old boats out there with traditional gunwales.

However. You could (as far as I know no one has ever done this yet) make gluelam ash gunwales not glued to the boat, that aren't fiberglassed.

Gluelam gunwales is the way I do it now. In the past I've glued the (gluelam) gunwale to the boat, as I make it, bending 1/4" strips onto the the boat with Titebond III in between the layers. Lots of clamps. And then I fiberglassed it. But you could duct tape visqueen to the side of the boat first. Then glue up with 1/4" ash or white oak strips, clamped over top the Visqueen with a box full of C-clamps.

Then take it off. Sand it up. Oil it. Put it back with stainless or monel bolts. If you want stiffness just make the gunwale a bit taller and/or fatter. Bending is easy because you are using strips. You don't need 4 gunwales, two inside and two outside. Just make two. Inside or out. Build up strips until it's stiff enough. You can make them a bit taller too, say a full 2 or 2-1/2" inch tall.

I have an engineering "Wood Products Handbook" somewhere complete with equations quantifying the increased stiffness (strength) you get from gluelams. I don't understand the math. It's a double integral where an equation is sent to another equation as a parameter. I only took one year of calculus. Differential equations happen in year two. But the bottom line is obvious. Gluelams are almost twice as strong as a single continuous piece of wood, of the same dimensions. Gluelams are the way to go. No matter what.


The first two times I did this I used epoxy to glue the strips and it was a sticky mess. It worked but it was messy. I do it with Titebond III instead of epoxy now and it's a lot easier to deal with. Clean-ups work with a drywall trowel and wet rags.
Re: Varnished vs. oiled
September 27, 2019 01:43PM
Good deal. Like that idea too. Either way if I go with glu-lam or traditional if I don't glass it would you recommend attaching them with bolts rather than epoxy to the actual side panel?

I made C's in calculus......I'll trust your word on strength of gunwales!
Re: Varnished vs. oiled
September 27, 2019 05:35PM
Re> bolting or gluing gunwales

I've done it both ways now. I'm like a shark. I have to keep moving and never do the same thing twice. What I like about bolting (everything) is that broken parts can be replaced. And stuff does break.
Re: Varnished vs. oiled
September 28, 2019 02:14AM
If you do elect to do the Glu-lam thingy and also decide to bolt it fast consider using a bedding compound such as 5200 so that you are benefitting from the strength of the whole and not just the point loads located at the bolts.

2#///)400
*_
n65-9#


That was early ancient math stuff. When youre further along in your understanding I'll explain it better
Re: Varnished vs. oiled
September 28, 2019 02:15AM
Brad are you going to use Plascore?
Re: Varnished vs. oiled
September 28, 2019 02:18AM
If you do elect to do the Glu-lam thingy and also decide to bolt it fast consider using a bedding compound such as 5200 so that you are benefitting from the strength of the whole and not just the point loads located at the bolts.

2#///)400
*
n65-9#


That was early ancient math stuff. When youre further along in your understanding I'll explain it better
Re: Varnished vs. oiled
September 28, 2019 04:09AM
5200 makes stuff impossible to get off. I prefer Dow 795 dowsil silicone. It holds and seals well. But you can pry it off when you need to.
Re: Varnished vs. oiled
September 28, 2019 12:01PM
Yes, good thinkin. 5200 must be carefully razored off and it takes forever.
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