**Keep new subfloor open to bilge drain??**

[skizman]

Hey guys. I putting a new deck on my 16ft tri-hull. Should I keep the subfloor open back at the bilge drain area in front of the transom so the subfloor can drain...if it needs to......OR....just glass it closed....and hope the new deck will stay dry and not leak underneath?
Always appreciate your advice!!

 

[jigngrub]

Re: **Keep new subfloor open to bilge drain??**

Your boat should have a deckwell, an opening in the deck at the transom in the center of the transom that will let any water that gets on deck drain down into the well and either be pumped out by the bilge pump or drained when the plug is pulled.

 

[skizman]

Re: **Keep new subfloor open to bilge drain??**

Yes that's what I have but where the aft deck meets the deckwell....should there be an opening between the deck and the hull so if there is a leak and water gets in there where the stringers and foam is......or....should I glass the subfloor closed(where the deck meets the deckwell so the deck/subfloor is all air tight??

Should the subfloor be able to drain water into the deckwell?
I don't know how else to explain it.
Thanks.

 

[jigngrub]

Re: **Keep new subfloor open to bilge drain??**

The area below your deck where the stringers and foam is should be airtight and filled solid with foam with no voids in the foam. This will displace and repel any water that tries to get in there, and there shouldn't be any water in there at all if you put your boat back together properly.

Putting a hole in the bilge well bulkhead to let what you call the subfloor drain will do more bad than good, it will let water into the area you don't want any water to get into.

If you glass your deck in properly like this diagram:

You won't have any problems with water getting into your below deck area unless you make the mistake of putting holes in it with a drill or screws which will cause rot and you'll be right back where you started in a few years.

What kind of foam are you using and how are you installing it?

 

[sphelps]

Re: **Keep new subfloor open to bilge drain??**

I would either close it completely or install a second drain through the transom . Build a bilge pocket to capture water from the deck . This is how my MFG is done . Rebuilding a tri hull and will probably do it the same way .

 

[jc55]

Re: **Keep new subfloor open to bilge drain??**

Okay, this is exactly where I was in my build a couple of months ago. If you have a stringer in the CENTER of your boat, this is a larger concern than if you have two, one on each side of center line. A tri-hull will most likely have a center stringer.

Long and short, check out my build. Mine was "sealed" but completely water logged. There was a hairline crack under the rear bulkhead that developed among other things.

I split my boat in two parts. The aft transom bilge isolated from the forward compartments. The two forward compartments connected via 1/2" cpvc glassed into the forward bulkhead, and two inspection/storage hatches over the lowest point in the hull.

You WON'T keep the water out. The factory couldn't do it, and you won't be able to. You might be able to postpone it if you pamper the boat and follow jignrub's great advice, but I will know about every drop that hits that bilge. That center stinger is going to be exposed...water comes in the rub rails, screw holes, penetrates tabbing, cracks develop, condensation, etc. You would have 5" of water before a bilge pump could help you because of the steep angle of the hull.

Ultimately it's up to you. Lots of great options now that you've entered the world of boat customization!

 

[Bondo]

Re: **Keep new subfloor open to bilge drain??**

Okay, this is exactly where I was in my build a couple of months ago. If you have a stringer in the CENTER of your boat, this is a larger concern than if you have two, one on each side of center line. A tri-hull will most likely have a center stringer.

Long and short, check out my build. Mine was "sealed" but completely water logged. There was a hairline crack under the rear bulkhead that developed among other things.

I split my boat in two parts. The aft transom bilge isolated from the forward compartments. The two forward compartments connected via 1/2" cpvc glassed into the forward bulkhead, and two inspection/storage hatches over the lowest point in the hull.

You WON'T keep the water out. The factory couldn't do it, and you won't be able to. You might be able to postpone it if you pamper the boat and follow jignrub's great advice, but I will know about every drop that hits that bilge. That center stinger is going to be exposed...water comes in the rub rails, screw holes, penetrates tabbing, cracks develop, condensation, etc. You would have 5" of water before a bilge pump could help you because of the steep angle of the hull.

Ultimately it's up to you. Lots of great options now that you've entered the world of boat customization!

Ayuh,.... The statement hi-lighted I completely Agree with,....

There's No such thing as a water-tight sealed compartment in our boats,...

I'm generally not a Foam kinda guy, but if yer gonna foam the hull,...

Provide Drainage of every square inch of the hull, to a single pumpable bilge,....

If ya Do, yer hull will last Twice as long,...
trapped water, Rots yer hull,...
Drained areas dry out, insteada Rottin',...

Use lotsa limber holes in the stringers, 'n bulkheads to provide the drainage to the bilge,...

 

[skizman]

Re: **Keep new subfloor open to bilge drain??**

Thank you for your comments. I will make sure that the stringer/foam area is closed up with glass and airtight. I originally asked about this because somewhere I read that that area below the deck should be able to drain if water leaks through somehow. If there was no foam in there, then I could see leaving it open to drain, but with foam it will stay wet forever and eventually start rotting the plywood above it.
I can't answer what materials I'm using because I can't afford all the good stuff, and don't want to hear all the negative comments about using cheap materials, but one thing for sure..............that new deck will be strong and last a long time!
Thank you gents!

 

[jbcurt00]

Re: **Keep new subfloor open to bilge drain??**

I can't answer what materials I'm using because I can't afford all the good stuff, and don't want to hear all the negative comments about using cheap materials...........

Ok, what inexpensive materials do you plan to use? It is important to most of us that you proceed wisely & safely, NOT to police what you spend on your rebuild.

Boat & boat resto safely.

 

[jigngrub]

Re: **Keep new subfloor open to bilge drain??**

Cheap, long lasting, and strong is an oxymoron as a rule and won't happen 99.9% of the time.

If you're going to jack-leg your boat together... then yes, it will be best to keep it to yourself... but it will not last. You don't have to take my word for it though, you'll see for yourself if this is your plan.

If you have a feasible way to put your boat back together economically so it will be safe and seaworthy we would be very interested in hearing your method.

 

[jc55]

Re: **Keep new subfloor open to bilge drain??**

Hey, we all spend our money on something. Some people invest in themselves with tools, training, knowledge, and memory making. Others on beer, cigarettes, alimony, and scratch off tickets. Both are at the boat ramp.

 

[jigngrub]

Re: **Keep new subfloor open to bilge drain??**

Hey, we all spend our money on something. Some people invest in themselves with tools, training, knowledge, and memory making. Others on beer, cigarettes, alimony, and scratch off tickets. Both are at the boat ramp.

The ones I find that're kind of disturbing are the ones that don't have enough money to build their boat right... but when it comes time to fill the boat up with gas and oil and run it around on the water to have fun, money is no object.:facepalm:

 

[jbcurt00]

Re: **Keep new subfloor open to bilge drain??**

It is important to most of us that you proceed wisely & safely, NOT to police what you spend on your rebuild.
Boat & boat resto safely.

I might have said that differently:

It is MORE important to most of us that you proceed wisely & safely, we're NOT trying to police how much you spend on your rebuild. Please boat & boat resto safely.

It doesn't matter to me how much anyone spends or doesn't spend on their project.

I also don't want to suggest/recommend that doing the work insufficiently, carelessly or in a manner that's unsafe to whoever is doing the work, or ultimately anyone who boards the 'repaired' boat, is a good idea, no matter the cost or time savings. I feel compelled to speak up.

I completely agree w/ the no money to do it 'right' philosophy Jig subscribes to.

It's also much more basic then that, IMHO. There is NO a gray area: it's either Safe or Unsafe. Period. IMHO.

As before:

Boat & boat resto safely

 

[skizman]

Re: **Keep new subfloor open to bilge drain??**

OK....so this is the run down on installing my new deck. I sliced up some insulation foam sheets(it has silver on one side)and filled up most of the space between the stringers, and then used 5 cans of Great Stuff-big gap to fill in all the small spaces. Then used Liquid Nails on top of the stringers, and laid in sections of half inch OSB plywood, and used stainless steel screws to attach plywood to stringers. Today I filled in any gaps...seams and screw holes with fiberglass putty. I'm still sanding.

Right now the floor feels nice and strong. Then I'll cut 4" wide strips of fiberglass cloth and glass that in on the whole perimeter where the plywood meets the gunwhale and also plywood seams...using Bondo Fiberglass Resin. My friend let me borrow a huge roll of fiberglass mat he had sitting in his garage. I'll then put 2 coats of that on the deck and run a couple inches-vertically up the sides.
And then paint the deck with a couple coats of garage/concrete floor epoxy paint. Then wait for the weather to break and go fishing on Lake Keowee.
I appreciate your honesty and your concern on doing things the right way with safety always on the top of the list. But all I can do.....is what I can do.....ya know.
"That's all folks!"

 

[jigngrub]

Re: **Keep new subfloor open to bilge drain??**

That's not the worst build we've seen or heard of, but it's far from optimum.

Keep your boat as dry as possible and you'll get a couple/few years out of that build. Keep your boat covered when not in use (a blue plastic tarp from Wal-mart will work) and keep the bilge well plug pulled when it's on the trailer so any water that gets in the boat can drain out.

The polyisocyanurate foam will keep your below deck area nice and warm, but isn't that good of a marine floatation material... but it'll work for a while if you keep your boat dry. The same goes for the great stuff foam.

Many here will disagree with me but OSB can actually be a decent boat building material, but you have to know what to buy and what to use with it. The OSB that uses the phenolic resin and is compressed into the desired thickness sheet and doesn't have one side sanded to obtain the desired thickness is actually pretty good stuff and doesn't have any core voids... but! The phenolic resin is an epoxy based resin and you have to use epoxy resin to lay the glass on it because polyester resin won't bond well to epoxy.
... but I suspect you bought the cheap OSB with the one side sanded smooth, and like the other stuff... it'll last for a little while as long as you keep the boat dry.

Depending on how well you take care of your boat will determine on how long this build will last, but your build is lacking in quality materials... but you already know that.

I wouldn't recommend this build for anyone that really likes their boat or is looking for a long term build, but since you're already in the process of doing it this way I wish you the best of luck.

Keep your boat DRY!

btw... use this non skid paint additive for your deck paint:
http://www.behr.com/consumer/produc...hr-premium-non-skid-floor-finish-additive-970

I just used it on some exterior wooden stair treads and it's really nice stuff and is very slip resistant. $5 for a bag that will do a gallon of paint.

 

[skizman]

Re: **Keep new subfloor open to bilge drain??**

Really nice of you to spend the time passing your great info to the public.
The boat sits under a roof/wing off the side of my shop. For the non skid paint additive....I use sand....strained through a metal strainer. I used it on my porch steps and works great. I think it's a waste to mix in in with the paint. so I just poof it lightly over the wet paint.
I sure have learned a lot!
Thank you!!!

 

[Gator1996]

Re: **Keep new subfloor open to bilge drain??**

Just another opinion, take it for what it's worth: I'm not sure how far along you have gotten on your repair but you may consider a bit more research on materials. I totally over analyzed every material purchase as I had an auditor (wife) looking over my shoulder. So I know what you are looking at.

When you consider the cost of great stuff foam and the panels that you cut up, you likely would have been 80% into the cost of the 2lb flotation foam that is recommended.

The Bondo resin will cost a lot more per gallon than what you can get through a fiberglass supplier, if you were doing a small repair, sure but a deck is gonna take a couple of gallons minimum, not too cheap when you buy by the quart, not too mention the sanding that you will have to do to get at the wax that is added into Bondo.

Also, the epoxy garage floor paint is comparable in price to a gallon of gelcoat. The epoxy may work just as well, I don't know, but I do know that gel is recommended on this site and others. I'm just saying that I bet you could have spent just a little more to take your repair to the next level easily. Again, just an opinion.

 

[skizman]

Re: **Keep new subfloor open to bilge drain??**

I really don't agree. I did my homework before I started this project. If I would of went with epoxy...2 part foam...gelcoat...good plywood...glass cloth and mat...it would of cost up to $200 bucks more. The wax in the resin is no problem because I'm not a great fiberglasser and I need to sand after each coat anyway to get the bumps ect..
Thanks.

 

[Gator1996]

Re: **Keep new subfloor open to bilge drain??**

Seems to me that if you are not too confident in your skills, you would want to use more efficient/safer methods. To each his own. I may be jaded about what a big difference is after doing my boat. In my mind $200 would be worth it in the long run.

I will say that foam can be had for a boat your size for at a local supplier in my area for $78.
White gelcoat can be had for $47 per gallon, same place
Poly Resin, same place $32.22/ gallon
Mat- It thought you had a source for that. Some biax tape would be an upgrade for your tabbing. $2.70/yd for 12" or $1.40/yd for 6"
not necessary I guess. Price from US Composites.
No reason to hash out the plywood thing. I was happy with Arauaco like most here are. The OSB thing is what it is I guess. Longevity is value though.

You would have bought the plywood anyway and you said that you had a source for mat so call that a wash. Supplies are gonna be the same or similar no matter what the materials chosen are. Any case with 2 gallons of poly and 2 gallons of gel, assuming you decided against the biax tape looks to be $240 or so. So I'm thinking your guess of $200 is a little high. Other prices sourced online not sure I can mention the name but it is Eastern Burlap. I got 99% of my supplies there. It is local to me so no shipping but did pay tax. Good luck.