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Foam and seat ventilation

Posted: Sat May 14, 2011 9:50 am
by rhenig
I am at the point were I can put the seat tops on the Bull's Eye side seats. The instructions say "foam flotation may be required". My first thought is, by whom and how would they know? That aside, what kind of foam should be used?

The instructions also specify ventilation to prevent expansion damage and suggest drain plugs work well. I'd like to find something that does not have a removable part that could get lost. Also, something that sit flush with no sharp parts that could cut legs or feet. Any suggestions on parts that have worked well would be great.

Also, I'd like to be able to install the plug before the top so I can seal it from the inside. I'm not sure I have room to do that given I need to fiberglass the seat top to the sides on the outside. If anyone has any tips on how they've dealt with installing the vents please do tell.


Re: Foam and seat ventilation

Posted: Sun May 15, 2011 10:14 am
by Rob Myran
I have been debating that as well. So far what I have decided is to leave it out until I have done some sea trials and sailed the boat. I built a full bulkhead between the cabin and the cockpit/locker area so water would not pour though the whole boat in a leak or knock down.

Now as to foam. My thinking is that I will put foam in. I plan on using pink sheets of 2" construction foam cut to fit in some areas. I also will likely use some expanding spray foam, however I will spray it into construction grade garbage bags pre-placed in the areas I want to fill with foam. I figure that if I need to remove that foam I won't have the mess of it adhered to the boat.

- Hope this helps your decisions.

Re: Foam and seat ventilation

Posted: Sun May 15, 2011 2:15 pm
by sunflounder
Nice work.

I decided against foam and put in some extra large ports backed with another layer of ply to allow access to the underseat area for storage and/or stuffing full of pool noodles if required. I did the same for the front bulkhead port and it came out ok.
I cut the holes with a zip saw thing ($20 at harbor freight) and kept the errors down with a string and screw in the center.

So if I just remember to unseal and seal the ports I should be ok : ()

The ports have an attachment point for a lanyard so the don't drift away. I got them at West Marine about $12 ea.

Doing the backing and hole drilling is way easier before you put the seat tops on.

If you do the big hole thing make sure to double check those clearances (another lesson re re learned).

Good luck on the build.


Re: Foam and seat ventilation

Posted: Mon May 16, 2011 8:47 am
by rhenig
Wow Dave, your boat looks great. I like what you've done between the inner and outer sheer with the alternating pattern.

What will cover the holes on the seat ends when you're underway? Same as the cover of the bulkhead? Also, I did a quick search on the West Marine web site and did not find those fittings. Do you recall what they are called?

And, I agree, remembering to open/close these things is the scariest part.

Hoping Mark C. chimes in with what he did (hint hint) :)

Re: Foam and seat ventilation

Posted: Mon May 16, 2011 10:56 am
by sunflounder
They are called deck plates in the west marine catalog, many different types and brands.
Yep used smaller versions of bulkhead plate on the seats.
I think Mark used them on the top of his seats. His well documented build was my inspiration and background screen during my build.
Mine is still hanging in the garage waiting for moving debris to settle and shop to be finished and rains to stop (recent move to pacific northwest from central CA) so no launch yet. Still finishing the dagger board and rudder (3rd tries).
Hope to get her launched by July and will post build pictures. Here's my getting ready to head north picture. Boat has 1k miles on it but no splash!

Hang in there


Re: Foam and seat ventilation

Posted: Mon May 16, 2011 3:27 pm
by rhenig
Is that a tow package for a Prius?

Where did you get the plans for the trailer?


Re: Foam and seat ventilation

Posted: Mon May 16, 2011 4:57 pm
by sunflounder

Well. sort of a towing package. The Curtis tow hitch people make a bolt on unit for the Prius II and I think for the III. No modifications required beyond a slit in the plastic shielding, works great. There is also an easy electrical set up. If you are interested check out the Prius trailer yahoo site at;

A trove of info and advice about the not officially recommended use of the Prius as a towing platform. My own experience is it works great, sucks up about 3-5 mpg vs 5-8 mpg cartopping with less damage to boat and car.

The trailer is a humongusly expensive unit from the Yakima car rack outfit that my wife bought me as a surprise to save my back (~$2K I'm way to cheap to buy such a thing and would have gotten a harbor freight cheapie). It works great as a car rack on a trailer but I still haven't figured out how to launch a boat off it. The trailer is way to high for direct launching which is a feature of its motorcycle like light load suspension and large wheels. I'm thinking of some sort of bicycle wheel attachment that will allow me to slide the boat off and hand wheel it to boat ramp or shoreline.
The bunks in the picture are the building supports modified to fit on the trailer which has T channels all over it so is easy to customize.
The trailer does fold up and stores in about 18" x 5' of space weighs ~150lbs and has a 250lb load capacity. Tows like a dream even over dirt and potholes as well as freeways, just have to keep reminding oneself there is an extra 16' behind you.


Re: Foam and seat ventilation

Posted: Mon May 16, 2011 9:45 pm
by Mark Chadwick
Hi Guys

I"m here but it sounds like you already figured it out.....I used 4in deckplates (Viking) in the tops of the seats as far aft as I could manage so I would not have to sit on them.

You can also get these nylon bags that sit inside the mounting ring, so you could put your cell phone, wallet, car keys etc inside and then screw the cover on so the items don't roll all around the length of the seat compartment. I didn't put any foam inside.

I leave the plates off when the boat is not in use. It is amazing the condensation that builds up inside when they are sealed. I need to get a set of spare covers because I want to drill a series of small holes in them. These will be for storage to keep mice out and still allow for some air flow.

By the way....your build is coming along great from your pictures! I do like the idea of putting your deckplates in the seat ends - easier to see all the way down to the other end if you have a need to take a look. Where I put mine I need a mirror to see along the length of the seat.


Mark C.

Re: Foam and seat ventilation

Posted: Tue May 17, 2011 2:33 am
by upspirate
Not one of the sailboats, but my skiff has the same set-up.

I wasn't that concerned about flotation, so I used these hatches which have an O-ring seal and will still work as sealing the chambers for flotation,but I can access the area for storage of docklines,flares, etc and still have some floatation. I will leave them open when not in use for storage.
I also used some ply for perimeter back-up so the screws won't be exposed on the inside
Bow chamber back-up

Re: Foam and seat ventilation

Posted: Wed May 18, 2011 4:07 am
by Stuart
Nice. Trailer is so cool.


Re: Foam and seat ventilation

Posted: Sat May 28, 2011 9:48 am
by rhenig
After looking around for a while I decided I did not want desk plates but wanted something that would not get lost. I went to the local plumbing store and after talking with the pro's about what kind of valves might work for this purpose I settled on a small cock drain. I build a recessed enclosure that I'll mount on the inside of the seat end. Part of my goal was to not have anything that would stand proud of the surface its mounted in so it would not get broken or scrape skin while moving around. I think this will do the trick.

I set a receiving nut in fillet, working on a sheet of wax paper. I used a small flat stick as a pallet knife to make sure I didn't get fillet on the threads.