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Built new thwarts

PostPosted: Mon Apr 12, 2010 8:22 am
by ctenidae
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1x8 mahogany. Cup holder baskets are made of cotton webbing stitched into a cross and screwed to the underside of the thwarts. Clearly, setting her up for cruising...

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Stencil for painting the name on- printed the letters, put a piece of vinyl bookcover over it, and drew the outline. Then peeled the paper off the back and stuck the vinyl on the boat. Now I have to cut each letter out.

PostPosted: Mon Apr 12, 2010 2:02 pm
by algonquin
Nice idea with the built in drink holders. Your project looks like it is coming along quite nicely. :) Brad

PostPosted: Mon Apr 12, 2010 2:05 pm
by algonquin
What year is your DS ? I see it has the old style wire horse traveler mounts on the rear coaming. Brad

PostPosted: Mon Apr 12, 2010 4:08 pm
by navahoIII
Nice job, but I wonder whether making such large holes in the thwarts compromises their strength.

PostPosted: Mon Apr 12, 2010 4:23 pm
by seandwyer
NavahoIII - I'd thought about the strength issue myself. I wonder if a couple pieces of flat iron screwed to the bottom - the length of the thwart - parallel to the direction of the beam would keep things nice and strong? I love the cup holders and would hate to see them disappear, although on my boat they would be bottle holders. Now I just need to find a handy place to mount the opener!

PostPosted: Mon Apr 12, 2010 5:40 pm
by ctenidae
navahoIII wrote:Nice job, but I wonder whether making such large holes in the thwarts compromises their strength.


Thought about that, but they are 1x8, and the forces are, I think, mostly going to be lateral. I think they'll hold- the ones I pulled out were 1x5 or so, and trashed- the seat end of one was completely loose and ragged. Unless we have some really heavy drinks in there, I think they'll be okay. Have 4 gymbaled holders to mount strategically as well. You can never have too many drinkholders.

They'll hold bottles just fine, too- the webbing underneath is thick enough nothing will slip through. I do have a bottle opener to mount, but haven't decided where yet. Maybe strategically placed underneath.

And, it's a 1962, near as I can tell. The wire traveller is gone, but the mounts remain. Some PO had rigged a Crosby on it, but now it's got a centerboom rig to the trunk.

PostPosted: Mon Apr 12, 2010 6:26 pm
by GreenLake
I agree, structurally there should be no issue. The loads can be handled by narrower strips of wood (equivalent to the edges) and unlike a scenario of isolated strips the material between them will counteract their tendency to buckle, making them stronger.

For loads outside the plane (heavy footed crew members) there's a loss of strength. Depends on the weight of your crew members and whether the cups will encourage them to place their feet somewhere else.

I must admit that my first reaction was "why didn't I think of that myself?". Your boat now has a certain air about it that will be very conducive to serious relaxation on the water.

One question remains: you write that you were using cotton for the netting. Aren't you afraid it might rot?

PostPosted: Mon Apr 12, 2010 7:21 pm
by ctenidae
GreenLake wrote:One question remains: you write that you were using cotton for the netting. Aren't you afraid it might rot?


It probably will eventually, but my backstop is it's $1 a yard, and easily removed. Shouldn't be getting wet by anything more than condensation off the glasses, relatively shaded by the thwarts and contents, and if they blow out after a year, no big deal, I'll just buy some nylon.

Besides, going with natural fibers is keeping it old school, right?

PostPosted: Mon Apr 12, 2010 7:30 pm
by GreenLake
I like cheap solutions...
Old school might have meant tarring them :D

Depends how dry your storage is, I guess.

You could always unravel a bit of old polyester or nylon rope and, presto, you'd be "reusing" :)

Anyway, nicely done, and enjoy your boat.

PostPosted: Mon Apr 12, 2010 7:47 pm
by GreenLake
seandwyer wrote:I wonder if a couple pieces of flat iron screwed to the bottom - the length of the thwart - parallel to the direction of the beam would keep things nice and strong?

Sean, the thwarts (whether modified or not) are weakest in the direction across the plane (sitting/stepping on them).

If you want to reinforce the thwarts, increasing the apparent thickness would be an effective method. For that you can use strips of similar wood, and get plenty of reinforcement for less weight than adding iron.

PostPosted: Mon Apr 12, 2010 11:21 pm
by algonquin
About the strength of the thwarts, as weird is this may sound, the holes actually add structural strength rather than detract from it. Of course too many holes may tip the scales the other way.

If you ever tried to tear a paper page with a perforated edge or for you that have been around long enough to remember when postage stamps had perforated edges and had to be licked (Yuck :x ) you know that they never tear along the perforated edge.

Even given that brief history of holes it would be wise to put in some additional support laterally as GL suggests. It would be better to overbuild rather than under build. Brad

PostPosted: Tue Apr 13, 2010 8:51 am
by ctenidae
I sat on the thwarts last night, nary a hint of flex. They're only spanning a 15 inch gap (not even, since that doesn't account for the end supports). Cracking a mahogany 1x8, even with holes, across that short a span takes either a sledgehammer or some serious Jackie Chan judo action.

Sanding down the coamings now, going to give them the same oil finish as the thwarts. Unfortunately, the floorboards are too far gone, and so got multiple heavy coats of spar urethane.

PostPosted: Tue Apr 13, 2010 12:50 pm
by GreenLake
Ahh, the empirical approach! :D

What oil finish did you end up using? And which PU?

Also, it would be nice to get your experience after a season or two.

For comparison, I've put a summary of my experience in a separate thread, so as to not hijack yours.

PostPosted: Tue Apr 13, 2010 2:20 pm
by ctenidae
We used the spar urethane that's made by Rustoleum- don't remember the brand name.

The oil finish is Minwax oil. We'll see how it holds up. I like the idea of just slopping more on if needed.

PostPosted: Tue Apr 13, 2010 3:07 pm
by GreenLake
That is the appeal of oil. While you will need frequent maintenance, it should be easy. When I got mine, the PO had used varnish, so I continued.

I take it, the spar urethane is a one-component oil based formulation?