Dory Floatation Questions

Getting ready to make the floatation blocks for my dory, and have a couple questions.

1) Do your floatation blocks stick out past the lip of the thwart board?  What thickness of foam did you use? 
 Page 92 of the manual shows gluing up (3) 1-1/2" thick pieces, creating a 4-1/2" thick block, which my measurements indicate would make the foam stick out past the edge of the thwart board, plus on page 93 it says the thwarts should overhang the foam by about 3/8". 

2) I can only find 3/4" foam sheets at my local home improvement stores.  Any suggestions on where to find thicker panels to reduce the number of pieces to glue together? 

3) To save epoxy has anyone used any type of building adhesive, or contact cement, to glue the pieces together?

thanks!

Curt 830/997-8120


14 replies:

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RE: Dory Floatation Questions

   No dory-specific answers, but "Gorilla Glue" is waterproof and works great on foam. It also creates a sorta soft glue line  that is fairly easy to sand or surform. I would rather use it than epoxy on foam in almost all cases.

RE: Dory Floatation Questions

2-part polyurethane expanding foam is also good stuff. It's closed cell, about 2 lbs per cubic foot, expands to exactly  fill the space and stcks to wood and/or epoxy. No piecing or gluing needed. Just mix 2 containers of liquid and pour into the cavity.

Here's the bow compartment of my sailing dinghy getting foamed.

Have fun,

Laszlo

 

RE: Dory Floatation Questions

   Thanks nemochad ...The ease of using Gorilla Glue may make using the thinner 3/4" panels an option for me.

Laszlo, thanks for the info, once cured, what kind of surfaces will pourable foam stick to?  Will it stick to a varnished bulkhead for example?  (That could be a good thing in this application)   I remember once I used pourable foam in the area under the floorboards of a hydroplane (like a CLC Cocktail Racer) and lined it with aluminum foil before pouring it so it could be removed and if I recall correctly, it stuck pretty well to the foil but that was a long time ago.

RE: Dory Floatation Questions

   I got my floatation at Lowes and it was 1 inch thick white insulating styrofoam-really inexpensive.  I glued it together with waterproof titebond to save on epoxy and that held fine.  3 pieces glued together gave 3 inch blocks which are perfect for gluing to the seats.  Coated them in epoxy so they won't dent up to much and painted them black as per CLC instructions.

RE: Dory Floatation Questions

Thanks PentwaterDave...I'll use pink or white 3/4" and Titebond III..actually using 3/4" I can do 5 layers and get 3-3/4" thick blocks...a little more floatation..should still fit under the thwarts...I bet CLC actually used (3) 1" boards like you did, not 1-1/2" like the manual says because a 4-1/2" block would stick out past the thwarts.  Thanks!

RE: Dory Floatation Questions

   has anyone thought of carving out in the floatation space under seats to put (and secure with cleats on the bulkheads) a few fenders? you can get polyform F fenders in 4 1/2 inch diameters and a few different lengths for around $12 each from hamleton marine in ME, mail order. it seems to me that having a space dedicated to a few fenders on board would be nice, they will float just as well, and as long as secured tightly when being stored (from both ends) they should perform the same duty as the floatationn they replace. One mught just put cheap plastic cleats on the bulkheads to tie them down. One could still have floatation built in around them so they just nestle in place. Has anyone else done this? any downsides. Also seems to me that the line securing them could be sized to be exactly what you need to drop them over the side when up against a dock so they would be very handy to use.

 

Thoughts?

 

 

 

RE: Dory Floatation Questions

DavidA...Excellent idea!  I've been entertaining all sorts of ideas...my thwart seat boards secure under the seat because I didnt want screw heads on the tops of the thwarts so I keep wanting to have a way to install the foam after installing the thwart panel..and I also wanted to store a half dozen fenders along the inner rails to use also as rollers on a beach plus at a dock, but that does take up space, so your idea of under the seat is excellent!     I just measured and it appears in a Dory you could fit (9) 3.5", or even 4.5" fenders that would sit on the floorboard (tied in like you suggested) and still have a couple inches of foam board under the thwarts, plus I could get at my screws under the thwarts even with them in place...I like it.  I wonder how much floatation a 4.5 x 16 fender provides compared to the foam board it replaces?

 

Curt  830/997-8120.

 

RE: Dory Floatation Questions

   I think ineviatably we will lose some floatation by doing this. and also my guess is that John at CLC will tell us that we should not replace permanent floatation with temporary, no matter how well attached.

but I am also planning on carrying a number of fenders and I dont want them just sitting around and I want them secured in a systematic way to give some bouyancy.  If I do this I may add some floatation under the bow section and put down a floorboard there on top. people always try to store stuff up in the bow and that is generally not a good idea since weight in the bow (where there is little bouyancy to counteract it) really messes up a boat's balance and trim. so putting floatation up there means there is just less space to add a lot of gear in the worng place.

 

if you still put some insulation floatation under thwaarts, this idea will eliminate the concerns that started this thread since you can now lay them down horizontally and customize your thickness under the thwart just by cutting.

RE: Dory Floatation Questions

   Funny you mention a floorboard in the forward section, I'll be doing that too.  John and I brainstormed ideas and  I ended up ordering a 2x4' piece of plywood plus some of that stock that the thwarts sit on to support it...my plan is to either let it sit on top of the mast step, or maybe raise it an inch or two above the mast step.  John did say that putting floatation under that fwd floorboard would be a perfect place to add more floatation, plus it will provide a way to step into the boat from there more easily if launching off a beach backwards. 

One other idea...you could drill a small hole in the buklhead, under the thwart board,  way out at the outer sides with a stopper knot on one side of the buklhead as a way to tie onto a fender on the other side of the bulkhead

RE: Dory Floatation Questions

   I would not use polystyrene (  styrofoam ) as it absorbs water. The best material seems to be polyurethane foam sold at Home Depot ,pink pather brand  2 inch thick

RE: Dory Floatation Questions

   megalops, thanks I'll return the white polystrene and get pink board.

So today I took DavidA's idea and picked up two 4.5" x 16" Taylor Made fenders and want to try tieing two of them in on the floor both on one side of one bulkhead..will tie well enough to act as floatation yet able to be untied if needed along side for a dock, or to use as a beach roller. Then with whatever space is left above the fender and under the thwart, I'll glue up some pink board and secure to the underside of the thwart..this also has the advantage of being able to use the limber holes to tie things down to the thwarts while traveling and not cutting into the foam because the rope would go around the fender, not foam.  Thoughts?  Curt 830/997-8120. 

RE: Dory Floatation Questions

   you're ahead of me, let us know how it all fits and works.

RE: Dory Floatation Questions

   Curt, did you try the fender idea or use foam throughout?

RE: Dory Floatation Questions

   I used 3/4" pink board throughout, and tied fenders to the inner rail and just flip them in the boat when not in use.

To conserve epoxy I glued the layers of foam together with Loctite PL-300 foam board adhesive.  I cut a notch thru the foam blocks and the bulkhead to allow straps to be fed thru under the thwarts to tie things down if need be:

I also added some glass on the bottom of the foam blocks in case I ever wanted to feed a tie-down line thru the limber holes and not cut into the foam.

I then glued the to the underside of the thwarts per CLC design. 

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