DIY Flotation Collar (side floats) to make your tin boat safer and more comfortable

Hi guys,

I want to share my DIY project because it will make any tin boat more stable and safe and not super complex to execute.
There was a lot of interest on the launch ramp with people touching the floats and giggling like they discovered something amazing.

My thread about the full conversion of this 12' 1976 Harber / Sears V-hull is here:
https://www.tinboats.net/threads/12-1976-harber-sears-v-hull-conversion.51128/page-2#post-510650

Making that boat heavier made it more stable, but it took 150 lb of the original flotation.
I decided to add flotation collars on both sides to add lost flotation back and make the boat more stable.



There are some versions of this built from PVC pipe or styrofoam, but I did not like the look or longevity of those.
I decided to use 4LB Cross-Linked Polyethylene (this is similar to EVA foam we use for decking but has fewer open cells and a more uniform surface)

I ordered 3x 1" 4LB Cross-Linked Polyethylene Sheets from foambymail.com. They deliver to US and Canada
https://www.foambymail.com/product/cross-linked-polyethylene-foam-4lb.html
This foam is firm and dense. I think 2LB version may work too, but it will be softer.

I asked them to cut it into 18 pieces of 72" x 8" x 1" at the factory.
The total cost was $447 CAD, which included custom cut, tax, shipping
I think the cost will be ~30% less if you ship to US.

This was enough for a 8" high x 6" wide and 8' long collar.
From what I could find, that adds 240LB of flotation (120LB per side).
Because foambymail.com had only 6' long sheets, I had to use 6' + 2' to get to my 8' collar.
I also took some pieces for another project and I have 1 piece left
so 14 pieces were used for this project.

To glue this foam, you can use a couple of products:
LePage PL 300 or LePage No More Nails Wet Grab

Wet Grab is the best option, but considering the area you need to glue, 300 is much less expensive if you use an 825 ml cartridge (I used only 2 of those at $14 CAD each)
I used 1 cartridge of Wet Grab to seal the bottom edge of the collar between the hull and the collar.

I glued the bottom 1/3 of the first strip to the hull because I already had a reinforcement aluminum bar there, and the hull is too rounded at the stern to get good contact.



If I did that again, I would probably use Wet Grab for 100% of the first strip surface and find a way to clamp to get a good surface contact.



In my case, I filled the large gap with LePage Tite Foam - it's super rigid after it cured for a day so I did not lose any strength there.



The next stripes were straightforward gluing with LePage PL 300 to the first one



You just have to make sure your clamping board covers 100% of the strip.



After 4 stripes were glued, I added 4 2' pieces to the front.



A better solution would be to use staggering 6' and 2' pieces so that the next one covers the connecting seam of the previous layer, but I decided to add 2' to the front only after I finished the main part.
An even better option is to use complete 8' stripes in the first place, but I could not find anyone who could sell and deliver that length to Canada at a reasonable price, so I improvised.

The next step was adding the last piece, which covered the seam, and trimming the edges to give the contraption a more "boaty" look.



I was considering painting this stuck but ended up covering the seams and the surface with DAP DYNAFLEX 230 Premium Indoor/Outdoor Elastomeric Sealant, Black - not sure how long it will last, but it's only $7 CAD per cartridge, and I used 2 cartridges to cover both collars. So far, it's still holding after a day on the water.

If I do it again, I will glue the last piece(s) from edge to edge because using the steps like that made the next part more complex: adding the reinforcement bad to the outside to tighten this to the hull.
I made the reinforcement bar out of 8' aluminum bar 2" wide and 1/4" thick and used stainless steel hex bolts (6" and 5" long) with a stainless steel fender washer and nylon insulation washer.






We already had the boat out on the water and had no problems going on the plane at 15+ knots with 2.5 people (2 large adults and 1 child).
The boat was super stable with both adults and the child sitting on one side to get the edge closer to the water so the child could reach the surface with his hand.
It felt like you would need another full-size adult staying right on the edge to get the water too close to the edge to be concerned.
I could not do much stability testing with a child on board but I'll do some the next time I get it in the water.

I hope you will find this useful, and let me know if you see any problems with this or have any questions.

Very unique. The finished fit looks incredible. Here are some questions if you don't mind. No reason other than just pure curiosity. When the boat is at rest, does the bottom of the collar sit right on the waterline? Is it above water when up on plane?

Good questions. I was so happy my little tin can did not instantly sink, I did not make too many pictures or videos for a more scientific data collection. Next time I'll do much more testing and will try standing on one of the floats.

> When the boat is at rest, does the bottom of the collar sit right on the waterline?

If I remember correctly, it was above the water in the empty boat and the rear feet or two was an inch or so under water when my fat *** dropped into the back seat.

> Is it above water when up on plane?

I'm pretty sure most of the float was above the water because 15 knots felt pretty smooth. I would probably notice if it was dragging. I'll check next time.

Because the floats are black, they are blending with the water.

Good job, looks like that could be beneficial in stabilizing smaller Jon boats.

overboard said:

Good job, looks like that could be beneficial in stabilizing smaller Jon boats.

Click to expand...

Thanks.
This should be easier to do on a jon boat. I think the sides there are straight and not curved like on v-hulls
It's possible the foam supplier can ship 3" thick 8" high pieces so you only need to glue 2 layers on each side instead of 5 I did.
you will need only 1 sheet of foam for
8' long x 8" high x 6" wide float on each side.
will cost ~$200

Well my Mom taught me if you haven't anything nice to say then don't say anything. So.....

LaqueRatt said:

Well my Mom taught me if you haven't anything nice to say then don't say anything. So.....

Click to expand...

I posted that project to get comments on what could be done better or if someone would spot any critical issues with that approach.
If you have something useful to contribute, please do.
What problems do you see with those floats?

How much do you estimate each of the collars weighs?

There is an Australian outfit called Kapten Boat Collars that makes a very similar product. Some of the videos on their website are pretty impressive. Here are a couple pics from their site.

LDUBS said:

How much do you estimate each of the collars weighs?

Click to expand...

I just weighed a piece of that foam. 106 grams for one linear foot of 1" thick x 8" high.
so, it's 106 grams x 8' = 848 grams per layer x 5 layers = 4,240 grams - 212 grams (2' missing on the last layer) = 4,028 / 4 kg / 8.8 lbs per side + glue and aluminum bar ~ 10 LBS per side
I used 4LB foam. I think 2LB foam will weigh half as much but be less rigid.

Each float is 5" x 8" x 96" = 3840 cubic inches which is 138 LB of buoyancy - 10 LB float weight = 128 LB of extra buoyancy per side.

LDUBS said:

There is an Australian outfit called Kapten Boat Collars that makes a very similar product. Some of the videos on their website are pretty impressive. Here are a couple pics from their site.

Click to expand...

Those Australian collars are very nice but will cost $2000-$2500+ USD with delivery, tax, and customs fees to Canada or USA
My version costs under $600 CAD / $440 USD, plus it was an easy and fun project to do.

waterant said:

I just weighed a piece of that foam. 106 grams for one linear foot of 1" thick x 8" high.
so, it's 106 grams x 8' = 848 grams per layer x 5 layers = 4,240 grams - 212 grams (2' missing on the last layer) = 4,028 / 4 kg / 8.8 lbs per side + glue and aluminum bar ~ 10 LBS per side
I used 4LB foam. I think 2LB foam will weigh half as much but be less rigid.

Each float is 5" x 8" x 96" = 3840 cubic inches which is 138 LB of buoyancy - 10 LB float weight = 128 LB of extra buoyancy per side.


Those Australian collars are very nice but will cost $2000-$2500+ USD with delivery, tax, and customs fees to Canada or USA
My version costs under $600 CAD / $440 USD, plus it was an easy and fun project to do.

Click to expand...

20 pounds total is a small price to pay for the floatation and stability gains. Well done!

Yeah, those Aussie ones are pricey. I watched one of the videos when they were taking a small boat through the surf like a surf board. Those Aussies might be a little nuts too! haha.

Quite a good concept, and nicely done.
I can't help but let my mind wander a bit about alternatives, and I think I can bring up a way to do it at lower cost. Seems to me standard construction foam would do the same job, at lower cost. Then, do something that the folks in the home-built teardrop camper world does, that they call "PMF". (Poor Man's Fiberglass) It's basically thinned down Titebond 2, painted on, with a layer of the cheapest painter's tarp you can get from Harbor Freight, or even bedsheets from Walmart, also painted on with the Titebond. That then forms a weatherproof seal over the wood walls. After it dries completely, then paint it the color of your choice. This method works quite well with foam too, as some tear-droppers are actually building out of foam for towing behind their economy cars.
The only problem I can possibly imagine is if one lets their small boat sit in the water for extended periods. (weeks-months) The immersion may then start softening the water-soluble Titebond.

Just my opine.....Roger

Years ago I remember a buddies dad had a canoe with something like that on both sides, I never thought much of it but did ask what it was all about and he said they used the canoe to go hunting up north, and the floats on each side made the boat impossible to flip so they would never be at risk of losing their guns or ammo while on the water.
For some reason I seem to remember it being a Sears canoe, it was painted to look like an old rawhide Indian canoe from the factory and the floats had bolts that were recessed into the foam with plastic cups or recessed washer about every few feet. The foam floats were about 4x4" or so and ran about 80% of the length of the canoe, spanning nearly the entire straight area on both sides. The foam was covered in some type of cloth that sort of resembled fire hose but a lot lighter. Another guy we knew had one with short outrigger floats on the sides for the same purpose.

GTS225 said:

Quite a good concept, and nicely done.
I can't help but let my mind wander a bit about alternatives, and I think I can bring up a way to do it at lower cost. Seems to me standard construction foam would do the same job, at lower cost.

Click to expand...

I considered construction foam, but a semi-decent one like FOAMULAR Rigid Foam Insulation Board 2" x 24" x 96" is $50 per sheet. Two sheets for two floats will be over $100 with tax. plus ~$60 for a gallon of good glue plus converting material.
so it will cost over $200 (at least in Canada), plus very messy work of covering with bedsheets, trimming, sanding, filling the gaps and painting.
If the water seal breaks, it will absorb water quickly and be a pain to remove and replace.
and there will be a gap in the seal because you can not rely on the glue and have to use thru-bolts to attach the floats to the hull.

For an extra $240 you can use the proper material that does not absorb water, does not need any covering or paint, and can bump into things without worries about breaking the seal.

Another option is a 6" DIA PVC pipe sealed on both ends. The front end can be heated and formed into something other than a flat pipe end, filled with Tite Foam; some brackets and straps over the pipe (to avoid the holes) can be used to attach the pipe to the hull and I'd put a drain plug at the end. Will cost approximately the same as construction foam without all the mess and will be much more rigid.

A number of years ago a neighbor had all new windows installed in his house, the windows came packed in 6" thick sheets of white poly foam, he was just piling it up out for the trash, so I gathered it up and saved it. I had a boat at the time that had foam filled bench seats with wood at the top. The original foam was likely poured in and then installed in the boat as an assembly.
I took a piece of the packing foam and weighted it down in bucket of water outside all summer to see if would absorb water. It did not. So I cut and glued up sections of that foam to fit snugly into the seat boxes of my boat after making new 3/4" plywood panels for the inside. The stuff was easy to work with a since its inside the aluminum there was no issues with UV light. Its now been about 6 years and the foam still seems good. I also left a piece of it about a foot or so square outside in the weather nailed to an old stump with a gutter spike to see how it holds up. So far that piece seems un damaged as well. (It appears to be the same foam they make those archery 'Cubes' from. My concern was more toward not loosing any strength in the seat more than flotation but it seems to work for both. From the start I knew I wasn't putting back the pour in type foam that it came with which was so degraded it would crumble like stale bread in my hand.

The idea of adding a foam collar to a boat sort of also reminds me of post on another site years ago where someone added two rear hull extension boxes filled with foam to add more flotation in the stern on a small aluminum boat. Both seem to achieve similar results but the collar idea ads more side to side stability I suppose.

GTS225 said:

Quite a good concept, and nicely done.
I can't help but let my mind wander a bit about alternatives, and I think I can bring up a way to do it at lower cost. Seems to me standard construction foam would do the same job, at lower cost. Then, do something that the folks in the home-built teardrop camper world does, that they call "PMF". (Poor Man's Fiberglass) It's basically thinned down Titebond 2, painted on, with a layer of the cheapest painter's tarp you can get from Harbor Freight, or even bedsheets from Walmart, also painted on with the Titebond. That then forms a weatherproof seal over the wood walls. After it dries completely, then paint it the color of your choice. This method works quite well with foam too, as some tear-droppers are actually building out of foam for towing behind their economy cars.
The only problem I can possibly imagine is if one lets their small boat sit in the water for extended periods. (weeks-months) The immersion may then start softening the water-soluble Titebond.

Just my opine.....Roger

Click to expand...

Back in the old days, seems they used canvas coated with varnish or paint on boat decks.

seahorse said:

Years ago I remember a buddies dad had a canoe with something like that on both sides, I never thought much of it but did ask what it was all about and he said they used the canoe to go hunting up north, and the floats on each side made the boat impossible to flip so they would never be at risk of losing their guns or ammo while on the water.
For some reason I seem to remember it being a Sears canoe, it was painted to look like an old rawhide Indian canoe from the factory and the floats had bolts that were recessed into the foam with plastic cups or recessed washer about every few feet. The foam floats were about 4x4" or so and ran about 80% of the length of the canoe, spanning nearly the entire straight area on both sides. The foam was covered in some type of cloth that sort of resembled fire hose but a lot lighter. Another guy we knew had one with short outrigger floats on the sides for the same purpose.

Click to expand...

meyers boats still make those. they now are sportspal canoes and the inside is also lined with same flotation.

Can you explain the reason they are mounted lower and not just under the top rail? Is it to make it more stable when not under power? If the purpose is to keep the boat upright in the scenario of a catastrophic boak sinking, it probably wouldn't matter. Is it to act like stabilizing outriggers floats like on some kayaks? Just wondering.

AlanT said:

Can you explain the reason they are mounted lower and not just under the top rail? Is it to make it more stable when not under power? If the purpose is to keep the boat upright in the scenario of a catastrophic boak sinking, it probably wouldn't matter. Is it to act like stabilizing outriggers floats like on some kayaks? Just wondering.

Click to expand...

I decided to mount just above the chin extrusion to provide more stability at slow speed and when not moving (loading at the dock or fishing). At high speed, those are above the water anyway.
If I mount those higher, they will start working at large angle so the floor will not be leveled at rest or low speed.
Following your example, those are more like outrigger floats.