Thwart repair

Topics primarily or specifically about the DS1. Many topics are of general interest, so please use forum sections on Rigging, Sails, etc. where appropriate.

Moderator: GreenLake

Re: Thwart repair

Postby GreenLake » Sun Sep 30, 2018 11:22 pm

If you asked me, I would change to coating with laminating epoxy instead of antifreeze and whatever else you were going to use. Especially as you could coat the inside of any pre-drilled holes as your drywall anchors apparently do not expose the threads, thus not breaking the epoxy seal. Red Oak is not particularly rot-proof wood, if I remember (in contrast to white oak).
~ green ~ lake ~ ~
GreenLake
 
Posts: 7136
Joined: Mon Jun 18, 2007 3:54 am

Re: Thwart repair

Postby tomodda » Sun Sep 30, 2018 11:35 pm

Yeah, honestly, I'm still ruminating on those cleats. The PO had bought white oak cleats to do the replacement, one is good, the other is crooked. I went to HD to get a replacement, but all they had was red oak. I may just ditch the oak and use offcuts of tropical hardwood. I have plenty, won't rot in our lifetimes, but I don't have any 78-inch lengths and it won't bend to fit the curve of the wall anyway. So maybe several short lengths? I have to expiriment.

Tom
tomodda
 
Posts: 825
Joined: Sun Aug 12, 2018 9:04 am

Re: Thwart repair

Postby GreenLake » Mon Oct 01, 2018 4:29 am

Using epoxy as sealant, the rot resistance of the wood itself should not as critical. But you do have to get that initial seal quite perfect and then protect the epoxy from UV. Unless you have a good source of specialized, naturally durable woods, it may be the easier approach. I've used it on the thwarts on my boat, and with good PU varnish that has UV inhibitors I've been able to avoid annual touch-ups / refinishing for several seasons now. The method works best if you can seal each piece entirely before assembly. Sealing the wood nearly eliminates the "working" of the wood (no more moisture cycling), meaning that varnishes will last longer as they do not crack from expanding wood. But you need to be rather thorough in application and topcoating (for UV protection) because if the epoxy ever fails, it's much more of a chore to get back to bare wood.

The opposite approach to wood preservation is to oil the wood. The oil won't last more than a season, but is very easily re-applied w/o the need to do a lot of prep as it doesn't build up. If you know you get around to annual maintenance, that might also be a good fit. I needed something more like coat & forget.
~ green ~ lake ~ ~
GreenLake
 
Posts: 7136
Joined: Mon Jun 18, 2007 3:54 am

Re: Thwart repair

Postby tomodda » Mon Oct 01, 2018 10:26 am

GL:

I agree with you on all points - carefully-done lamination works well, varnish is a pain, oiling is nice but requires yearly redo. Warning - encasing in epoxy does not save you from dry rot, but that's a whole other story.

However, for me personally, I don't get along with epoxy - acquired allergic reaction (hives) due to not being careful enough during past boat-building. I still use it in very small quantities and with respirator, etc, but really don't want to do extensive lamination work. Which is why I decided to rehab a DS1 instead of build (another) stitch-and-glue boat.

So, about the seats, I'm using 1-by Cumaru planks (aka Brazilian Teak) from advantagelumber.com. I've done various deck projects around the house using their wood and am very happy with them and the product. Basically, the tree grows in swamps in the Amazon. Advantages of Cumaru:

-Never rots, at least not in our lifetime.
-It's pretty :) A reddish color. Looks great when rubbed down with teak oil. I personally don't mind refreshing oil every few months.
-Doesn't splinter
-Very dimensionally stable - wet, dry, it doesn't move.
-FWIW, it smells good (like vanilla) and is highly fire-resistant.

Disadvantages:

-It's heavy. I'm fine with it, but if I ever want to race my #37, I'll swap the seats out for pine.
-It's extremely dense, so a pain to work with - eats up saw blades, breaks drill bits, dulls router bits. In practice, you just need to be extra-careful of your tools when working this wood. But if you're building an entire deck out of it, budget for extra circular saw blades.
-It's brittle. It doesn't bend at all, but if you put enough force on a small enough piece (less than 1x1 inch) then it just shatters.
-Expensive! Of course, epoxy is also expensive, as is my time and health in spreading toxic goop around. Anyway, cost/benefit ratio is up to each individual.

Anyway, for my thwarts and seats, the advantages outweigh the disadvantages - at least for me - and it's a relatively small project. I'm throwing all this out there in case anyone else is thinking of doing woodwork on a DS1 and wants to minimize epoxy use. No way you can use Cumaru to make new coamings (because of the curve), but I'm making new floorboards with the wood "as long as I'm at it." Cumaru just laughs at being submerged, no rot.

Ok,this has been a long digression to a digression! Looking forward to seeing what @Cliff does with his seats.

Tom
tomodda
 
Posts: 825
Joined: Sun Aug 12, 2018 9:04 am

Re: Thwart repair

Postby GreenLake » Mon Oct 01, 2018 2:43 pm

@tomodda: thanks for sharing the detailed explanation.
~ green ~ lake ~ ~
GreenLake
 
Posts: 7136
Joined: Mon Jun 18, 2007 3:54 am

Re: Thwart repair

Postby tomodda » Mon Oct 01, 2018 2:47 pm

Overdetailed! Anyway, I'll post photos as work progresses.
tomodda
 
Posts: 825
Joined: Sun Aug 12, 2018 9:04 am

Re: Thwart repair

Postby Cliff » Tue Oct 02, 2018 3:00 pm

Sunbird Seat & Thwart 2.jpg
Sunbird Seat & Thwart 2.jpg (38.72 KiB) Viewed 9924 times
TY for the in

My thwarts are in two pcs 29.5" long each. The thwarts connect into the centerboard housing at a seat fiber glassed onto the CB housing and to a wood rail along the side which supports the outside of the seat as well.The end of the seat buts flush to the thwart. I found a picture on the forum site by "Sunbird" (attached) but can not see the way it is connected below. There are two bolt holes on the thwart and three parallel on the seat. I believe these were by the Marscot Plastics but when I got it, it was held together by what looked like an old screen door hinge. Looking at the bottom of the seat it is filled with many holes. I bought the boat 2'nd hand in the early 70's. (Hull # 2018)

My original mahogany seats are split, held together by some funky picture frame type brackets. I've had new seats milled from hardwood about 20 years ago but never replaced them. The boat was last registered in 1992. Used to moor it at my camp on Newfound Lake in NH (no longer own camp). Am I a procrastinator?? you bet but I'm retired now and wish to put the old boat back in service.
Cliff
Cliff
 
Posts: 51
Joined: Thu Oct 27, 2011 3:20 pm
Location: Andover, MA

Re: Thwart repair

Postby Cliff » Tue Oct 02, 2018 3:20 pm

tomodda wrote:GL:

I agree with you on all points - carefully-done lamination works well, varnish is a pain, oiling is nice but requires yearly redo. Warning - encasing in epoxy does not save you from dry rot, but that's a whole other story.

However, for me personally, I don't get along with epoxy - acquired allergic reaction (hives) due to not being careful enough during past boat-building. I still use it in very small quantities and with respirator, etc, but really don't want to do extensive lamination work. Which is why I decided to rehab a DS1 instead of build (another) stitch-and-glue boat.

So, about the seats, I'm using 1-by Cumaru planks (aka Brazilian Teak) from advantagelumber.com. I've done various deck projects around the house using their wood and am very happy with them and the product. Basically, the tree grows in swamps in the Amazon. Advantages of Cumaru:

-Never rots, at least not in our lifetime.
-It's pretty :) A reddish color. Looks great when rubbed down with teak oil. I personally don't mind refreshing oil every few months.
-Doesn't splinter
-Very dimensionally stable - wet, dry, it doesn't move.
-FWIW, it smells good (like vanilla) and is highly fire-resistant.

Disadvantages:

-It's heavy. I'm fine with it, but if I ever want to race my #37, I'll swap the seats out for pine.
-It's extremely dense, so a pain to work with - eats up saw blades, breaks drill bits, dulls router bits. In practice, you just need to be extra-careful of your tools when working this wood. But if you're building an entire deck out of it, budget for extra circular saw blades.
-It's brittle. It doesn't bend at all, but if you put enough force on a small enough piece (less than 1x1 inch) then it just shatters.
-Expensive! Of course, epoxy is also expensive, as is my time and health in spreading toxic goop around. Anyway, cost/benefit ratio is up to each individual.

Anyway, for my thwarts and seats, the advantages outweigh the disadvantages - at least for me - and it's a relatively small project. I'm throwing all this out there in case anyone else is thinking of doing woodwork on a DS1 and wants to minimize epoxy use. No way you can use Cumaru to make new coamings (because of the curve), but I'm making new floorboards with the wood "as long as I'm at it." Cumaru just laughs at being submerged, no rot.

Ok,this has been a long digression to a digression! Looking forward to seeing what @Cliff does with his seats.

Tom


Tom

Have had seats milled out to rough shape. The wood is a hardwood laminated longitudinally. The inside edges have been rounded and now need to do some fine shaping to the area of the thwat. Now have a good idea for the joint.Expect to use a metal (SS) one piece bracket drilled to match the large (3/8" dia) holes in the two pieces. The inside of the seat has no supports between the Thwart and the stern rail support.I believe that the original boat was free of supports also but when I last sailed it I felt it could use at least one intermediate support. I see on your pic you have some intermediate supports.

Cliff
Cliff
Cliff
 
Posts: 51
Joined: Thu Oct 27, 2011 3:20 pm
Location: Andover, MA

Re: Thwart repair

Postby tomodda » Tue Oct 02, 2018 3:24 pm

Procrastination - Never put off until tomorrow that which you can put off until next week!

Anyway, sounds like your only problem is how to connect the seats to the thwarts. Ditch the screen door thing and get some deck joining plates from the HD, rummage around you'll find the right piece (big rectangular plate). They are meant to be nailed, but drill some of the holes out and screw them instead. Yeah, they are galvanized instead of SS, but you wont see them and they wont rust. Spray with some rustoleum if you're worried and just check them every year or so.

Best,

Tom
tomodda
 
Posts: 825
Joined: Sun Aug 12, 2018 9:04 am

Re: Thwart repair

Postby GreenLake » Tue Oct 02, 2018 4:15 pm

If you drill galvanized, those hole will rust some - may not be an issue for freshwater boats. In saltwater all problems are magnified.
~ green ~ lake ~ ~
GreenLake
 
Posts: 7136
Joined: Mon Jun 18, 2007 3:54 am

Re: Thwart repair

Postby Cliff » Tue Oct 02, 2018 4:32 pm

tomodda wrote:Procrastination - Never put off until tomorrow that which you can put off until next week!

Anyway, sounds like your only problem is how to connect the seats to the thwarts. Ditch the screen door thing and get some deck joining plates from the HD, rummage around you'll find the right piece (big rectangular plate). They are meant to be nailed, but drill some of the holes out and screw them instead. Yeah, they are galvanized instead of SS, but you wont see them and they wont rust. Spray with some rustoleum if you're worried and just check them every year or so.

Best,

Tom


Tom

Were the supports along your seats original? I just went to the basement and measured the old mahogany seat thickness @ 7/8". My new seats are a full 1" thick and I'm thinking they may be stronger and stiffer than the original seats. Not sure but the wood looks like Ash--Also checked closer and the wood is not laminated but one plank--long time since I bought it. I plan to use the old thwarts with the new seats--My check of wood strength is that ash is stronger than mahogany--also weighs more(Specific gravity: ash 0.60 and mahogany 0.45) I don't think the extra weight should be too much of a problem.

Cliff
Cliff
Cliff
 
Posts: 51
Joined: Thu Oct 27, 2011 3:20 pm
Location: Andover, MA

Re: Thwart repair

Postby Cliff » Thu Oct 04, 2018 7:38 pm

Tom

Were the supports along your seats original? I just went to the basement and measured the old mahogany seat thickness @ 7/8". My new seats are a full 1" thick and I'm thinking they may be stronger and stiffer than the original seats. Not sure but the wood looks like Ash--Also checked closer and the wood is not laminated but one plank--long time since I bought it. I plan to use the old thwarts with the new seats--My check of wood strength is that ash is stronger than mahogany--also weighs more(Specific gravity: ash 0.60 and mahogany 0.45) I don't think the extra weight should be too much of a problem.

Cliff
Cliff
Cliff
 
Posts: 51
Joined: Thu Oct 27, 2011 3:20 pm
Location: Andover, MA

Re: Thwart repair

Postby tomodda » Fri Oct 05, 2018 12:02 am

Yes, c-shaped supports were original. Ditto the cleats along the sidewalls. Haven't measured the seat thickness, I will if you want.

Tom
tomodda
 
Posts: 825
Joined: Sun Aug 12, 2018 9:04 am

Re: Thwart repair

Postby GreenLake » Fri Oct 05, 2018 3:07 pm

Somehow, I don't think those supports would be called "cleats". But what is the correct name. Are they stringers (going lengthwise)?
~ green ~ lake ~ ~
GreenLake
 
Posts: 7136
Joined: Mon Jun 18, 2007 3:54 am

Re: Thwart repair

Postby tomodda » Fri Oct 05, 2018 4:29 pm

Well, as long as we're picking nits (my favorite game!),

Miriam-Webster:

cleat noun
\ ˈklēt \
Definition of cleat (Entry 1 of 2)
1a : a wedge-shaped piece fastened to or projecting from something and serving as a support or check
b : a wooden or metal fitting usually with two projecting horns around which a rope may be made fast
2a : a strip fastened across something to give strength or hold in position

as opposed to:

stringer noun
string·er | \ ˈstriŋ-ər \
Definition of stringer
......
4a : a long horizontal timber to connect uprights in a frame or to support a floor
......
5a : a longitudinal member extending from bent to bent of a railroad bridge and carrying the track
b : a longitudinal member (as in an airplane fuselage or wing) to reinforce the skin

So, a cleat holds something, while a stringer is to re-enforce another surface (like the hull) or structure (the floorboards). The bumps in the bilges of older DS1's are stringers, even the rebar in the edge of the cuddy could be considered a stringer. The wedges that some folks put under their cam-cleats are cleats. However, also looks like a cleat can be a stringer "to give strength," but I don't think a stringer can be a cleat. I dunno, ask Webster! :)

OK, this nit is thoroughly picked! In reality, they are pretty much interchangeable terms.

Tom
tomodda
 
Posts: 825
Joined: Sun Aug 12, 2018 9:04 am

PreviousNext

Return to Day Sailer I Only

Who is online

Users browsing this forum: No registered users and 18 guests