New - Boat build advice

RM Anderson said:
Eric, I guess what I'm saying is why let water accumulate in the bilge in the first place? With a completely sealed floor, the water would all run to the stern (engine well). An example would be the Boston Whaler in which the hull is filled with foam. Perhaps scupper holes would be a better term than limber holes in first post. With stitch and glue, "We are unburdened by what has been".
Too soon? Richard
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That is a very large area to completely seal. Temp variations will cause it to pressurize and depressurize and who knows what that would do to the hull. Could lead to bulging and cracking after enough hot/cold cycles. God, here I go again. Foam has no place in the floor of a boat. A swamped boat with the center of buoyancy below the center of gravity will flip if the boat tilts enough. Passengers will be clinging to a turtled hull in frigid water. I strongly discourage putting foam flotation under the floor. If you think the floor in my Black Brant is sealed from looking at the photos with the deck hatches, well it isn't. There are limber holes at the front and rear. Water passes through and there is a bilge pump pickup in the lowest area midship.
 
Eric Patterson said:
That is a very large area to completely seal. Temp variations will cause it to pressurize and depressurize and who knows what that would do to the hull. Could lead to bulging and cracking after enough hot/cold cycles. God, here I go again. Foam has no place in the floor of a boat. A swamped boat with the center of buoyancy below the center of gravity will flip if the boat tilts enough. Passengers will be clinging to a turtled hull in frigid water. I strongly discourage putting foam flotation under the floor. If you think the floor in my Black Brant is sealed from looking at the photos with the deck hatches, well it isn't. There are limber holes at the front and rear. Water passes through and there is a bilge pump pickup in the lowest area midship.
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Whats sad is how many aluminum duck boats have foam in the floor because they have to have x amount to be coast guard compliant if its a true flat bottom. So thats my next question, how do you all ensure the coast guard compliancy with these home builds? how do you go about getting a home built boat registered?

Maybe dont answer all these questions though... YOU MF'ers gonna make me build a boat and theres gonna be a havoc for sale soon.
 
Eric Patterson said:
That was how I did my Scaup. The above is my Black Brant. Before I sold my Scaup I had to rework the knees into chine-to-chine bulkheads. I call them cockpit cutout bulkheads The trough, as I called it, did allow water to pass but so do limber holes and I think what Tod showed above is a stronger better solution if you use a keelson.

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I didn't use a keelson in my Black Brant as it is not called out in the plans. It has been my observation, from my own boats, and others posted here, most flexing is port to starboard and not stem to stern. Creating what I call cockpit cutout bulkheads and bonding the floor to them makes for a VERY RIGID structure. When you notch the floor into the cockpit bulkheads and glass all of it you lock everything together. That's my recommendation for the floor.

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Thanks!
 
William Reinicke said:
So thats my next question, how do you all ensure the coast guard compliancy with these home builds? how do you go about getting a home built boat registered?
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The rigors and process vary from state-to-state. My state is fairly lax and CG requirements were not assessed to my knowledge. I think they were mostly concerned about obvious issues and placement of the hull ID plate (sticker).
 
If you want "Level " flotation when swamped, your foam or whatever you choose to displace water should be high, next to the gunnels. Any boat boat will quickly "turtle" whether the bilge is filled with foam, air or water. I learned this many year ago when I was into white water canoeing. Richard
 
RM Anderson said:
I am an amateur builder but one question I have never found an answer to is why direct unwanted water to the bilge in the first place? Since a boat with outboard naturally rides lower in the stern, why not direct water to the motorwell with limber holes above the waterline? I believe this is an unnecessary carryover from aluminum boats that are impossible to seal. That would eliminate all the gunk that accumulates in the bilge and simplify wood sealing. Richard
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It just isn't practical in a dedicated duckboat given the measurements I've taken on mine. I was not aware of self bailers when I built, having grown up inland in tin boats, but I have considered converting my boat since. The floor would have to be much higher to get it to work and you would lose a lot of concealability with the floor that much higher to get a predictable self bailing boat. Additionally, these boats are like surfboards driving them, adding height to the floor would make it worse.

If someone really wanted to that could happen. I suggested it as an option the other day, but the trade-offs are severe.
 
HenryHawthorne said:
I may be mis-using terminology. The plans call for a 1.5" wide keelson between the 3rd and 6th bulkhead - right down the centerline (lowest point side-to-side).

@Eric Patterson - somewhere here I'd seen a picture of a boat with what amounted to 2 longitudinal below the sole, each a couple inches off the keel and mistakenly recalled it being from your Scaup build. Looking at the thread you linked I was obviously wrong, as that doesn't have what I'm calling a keelson at all. I'll dig around and see if I can find it, but after looking at Tod's picture again I'm probably overthinking it and should just stick with the single keelson with lateral limber holes as suggested.
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On the snow goose the keelson may be specified or maybe I added it. The span side-to-side on a snow goose is a lot larger than a black brant. I think it would be ideal not to have a keelson if you didn't need one, but you may need one for floor strength. The keelson, as Eric said, is not adding a bit to strength to the keel the way these boats are built since the keel buildup is so robust with the "V"ed ply and the glass. My boat drains really well as I said with a single keelson with limber holes along the length and at bulkheads.
 
Eric Patterson said:
The rigors and process vary from state-to-state. My state is fairly lax and CG requirements were not assessed to my knowledge. I think they were mostly concerned about obvious issues and placement of the hull ID plate (sticker).
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In Louisiana. A warden comes out and does a inspection of the bat and inspect's the receipts for all materials used to build the boat.

Not once did they check if I had actually put the foam in my boats. I mean I did put, they didn't do anything to check that I did.
 
tod osier said:
On the snow goose the keelson may be specified or maybe I added it. The span side-to-side on a snow goose is a lot larger than a black brant. I think it would be ideal not to have a keelson if you didn't need one, but you may need one for floor strength. The keelson, as Eric said, is not adding a bit to strength to the keel the way these boats are built since the keel buildup is so robust with the "V"ed ply and the glass. My boat drains really well as I said with a single keelson with limber holes along the length and at bulkheads.
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It's interesting. It is drawn in and noted on the construction view drawing, but not listed in the materials list nor on any other drawing. To your point, I do wonder if it is included because the design otherwise would have no sole support between the 3rd and 6th bulkheads. Converting 4 & 5 from knees to bulkheads provides support, so the keelson may not be necessary at all. I'll think on that when I get to that stage.

I did get a note back from someone on the Devlin team confirming the hull and side specs had been changed from 3/8" to 1/2" - but that I'm good building with 3/8" if I prefer. I do.
 
I'm always confused with foam, no foam, under floor foam and under gunnel foam. Every boat I've ever bought has flotation foam under the floor. That's not going to be a level floating boat. It's going to roll over. A couple boats I've had have had stern pods and bow casting floors have additional flotation. The regs don't specify where flotation is supposed to be applied yet it states level flotation is required in the size boats I've owned. Everyone has an opinion and it's seems different from the coast guard regulations. Then there are wooden boats. Doesn't wood float? Just add a flotation bag to compensate for the weight of the motor!
 
Ed

My advice for no foam or sealed areas under the floor is based on physics, not CG regs. I've had people disagree with me over they years, but I'm not changing my position. Archimedes was no idiot, and Jeff Smith walked me through the principles many years ago. In a conversation with Sam Devlin he too agreed flotation has no business below the floor. His designs all use three point flotation.

You may remember the tragedy on Saginaw Bay some 30 years ago when Jim Cripe's top heavy Outlaw boat was swamped and capsized killing all the occupants. Guess where he put his flotation. Yep, under the floor. Jeff Smith discussed with Jim his foam placement and the risk involved over the phone about the time the Outlaw boat was introduced to the duck hunting market. Jim Cripe touted his Purdue engineering degree to Jeff and argued how foam did the most good if it was the first thing submerged. Jeff told him he was an idiot. Jeff, son of a Stanford physicist, had an IQ of over 175 and an incredible knowledge of college physics and engineering principles. His argument had far more merit than Jim's, and the result speaks for itself.
 
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