Boat collars

[Molokai]

This seems like a great idea. These are only available through a company in Queensland Australia so the shipping is astronomical and they're kinda pricey to begin with. Only just saw these but appears to increase stability, load capacity and general seaworthiness. Also keeps spray down. What do you guys think?

[youtube]9Octqbs4B8Q[/youtube]

 

[Fire1386]

Wow, that appears to make a great difference, will take a look at the website later this evening.

 

[surfman]

Kinda one of the reasons I never liked the v-hulls, my BIL has one and it is definitely tippy.

 

[Molokai]

I've been looking for something to make my Jon more seaworthy but this also looks like it would make a casting deck a lot more stable. Big $$$ for this. Surprised there isn't a US manufacturer.
More info. Hope im not breaking any rules. I have no affiliation with this company

[youtube]vnnP3Tv9mTQ[/youtube]

 

[Shaugh]

This looks like his prototype.

Making your own similar device would be very simple out of closed cell foam like this:

https://www.foambymail.com/MC2-/cross-linked-polyethylene-foam-2lb.html

you would need to glue it up out of layers. It appears to be held to the hull by long bolts but you could probably come up with a way to take them on an off easily... use them only when you needed it.....

 

[Fire1386]

They are pretty pricey, ouch, and that doesn't include shipping :shock:

 

[Molokai]

From what i gather he gets the foam from Asia in long lengths. Apparently splicing isnt ideal. Not sure why but that seemed to be some justification for his price.
But like Shaugh pointed out the foam is available and could pretty easily be glued together and if you overlapped every other layer it seems a splice would work just fine. It is glued to the boat after removing paint with green label Liquid Nails construction adhesive as well as a few plates and bolts. I dont know much about these materials but this has potential. 8)

 

[Shaugh]

you'd be surprised how strong a couple lines of 2" adhesive Velcro is... I bet it would work and you wouldn't need to mess up your boat.... Personally I would end it well back from the bow... IMO it could end a little after the start of the bow curvature and you wouldn't lose anything. You can cut the stuff very easily with a saw...

 

[Molokai]

I agree. No need to go all the way to the bow. Comes in 6' lengths...that should be plenty. Here on Molokai there is the longest fringing reef in Hawaii. Lots of shallow flat expanse so a jon boat is perfect. My problem is on occasion i have to transit some open ocean stretches. Not sure if i'd feel safe with velcro. :lol:

 

[Shaugh]

Another idea would be to cut and sew shaped covers out of heavy outdoor PVC mesh and fill them with loose sheets of foam. I've made several boats that way:

If you're interested I could help you plan it out...

 

[Molokai]

Wow Shaugh! Some innovative thinking! I saw on the foam dealer's site there was a skin to glue on the foam for a tougher shell. The PVC mesh might be an alternative to that. Are the pontoons on that little craft in the photo made that way? What kind of paint did you use?

Im going to get informed on cross linked polyethylene foam, surface prep for glueing ect and figure out how i want to approach this. I think im going to start with custom bolt on pods to begin with. The foam collar could easily extend alongside them.

 

[Shaugh]

Pontoons are covered with pvc mesh fabric... like the stuff you see on the backs and seats of outdoor chairs and awnings... easy to buy at places like this:

https://www.fabricguru.com/index.php?dispatch=categories.view&category_id=1731

Super strong and will last for decades in salt water..

Let's call these outriggers... outriggers could be easily and strongly attached to the boat by sewing a long tunnel on the corners facing the boat. Then you could put a couple 1" x 1/8" aluminum bars through them. The bar could be bolted to the hull. much better engineering than liquid nails...

We could probably use very inexpensive insulation foam inside the covers... like the blue stuff at home depot. That stuff is ultra light weight and indestructible too.

Basically you are creating a fabric cover with a zipper... like a seat cushion on a sofa.... but shaped like the outrigger...

I could provide you a diagram to cut the fabric.. then you take it anywhere they sew things... awnings... boat covers... furniture re-upholstery shops etc. Show them the diagram and ask them to sew it up for you... I doubt it would cost much...

Maybe we could go into business if it works well ? These would be much better than what he's doing.. at a fraction of the cost...

 

[Molokai]

Sounds very sturdy. I like the attachment idea. Do you have any more pics of boats you've put together this way?

 

[Shaugh]

Not many relevant photos. This is the basic idea I have. Of course I would modify it to your preferences. From this I could generate a cost estimate and a diagram of the pieces to be cut and sewn.

If anyone else has ideas feel free to add them... Looking at your boat it would also be possible to size this pattern exactly to the shape of the upper side if you provide me a diagram of those measures :

For a pair of 12 foot outriggers you'd need about 6 sheets of this:

https://www.lowes.com/pd/Dow-R5-Faced-Polystyrene-Foam-Board-Insulation-Common-1-in-x-8-ft-x-4-ft-Actual-0-937-in-x-7-812-ft-x-3-75-ft/3050997

 

[richg99]

Sounds like a great idea aborning.

Many years ago, Sears was selling a canoe. Its sides had tough rubbery foam slabs running the length of the boat. They were attached with large, maybe four or five inches wide, plastic-headed "rivets", as best I can recall. The thick shaft of the "rivet" extended inside of the boat sidewalls.

I presume that their reason for being attached was similar to the video. Added flotation and added stability.

Let's see some prototypes. regards, richg99

 

[Molokai]

Been battling a cold and trying to get educated on foam and all the aspects of collars on aluminum boats. I'm not really 100% sure of all of what ive found but here it is anyway. :lol:
The guy in OZ also builds boats and his thing is reversed chines and how they improve handling in rougher water. The collars he makes form a reverse chine which also deflects wave spray, making for a dryer ride. Less water in the boat is also a plus. Done properly these collars have a number of benefits. Conversely, done wrong they can produce cavitation and ill handling effects. Almost all the boats i see are v-hulls with his collars on. I believe flat bottom boats would be less affected by the collar placement but thats only speculation.
Since placement is fairly important i would imagine that making the collars as structural as possible would be important. IE the collars moving even a little could mean unpredictable behavior. Not good. I think this is why the collars are glued on and then held in place with hardware. The gluing process seems pretty detailed with hull prep and prepping the foam. All irregularities on the boat must be matched on the foam to ensure a tight fit.
The foam itself (cross linked polyethylene) is very strong but from what i gather it's achilles heel is UV rays. Sunlight breaks this stuff down fairly quickly which is why a skin must be glued on the collar to prevent this. From the websites i see selling foam the longest piece (skin or block) is 72". Shaughs method of a sewn pvc bag is a great solution but i have two concerns: 1. The mesh may let in UV and break down the foam, This could be alleviated with using the insulating construction foam suggested. 2. Movement of foam inside bag. The foam (whatever type) would need to be glued together to form one block and then somehow bonded to the pvc mesh. I dont see why this couldnt be done. Some kind of resin (epoxy) to make the pvc mesh adhere to the foam making it structural and being scuff resistant.
Last concern is always a big one. Drilling as few holes in the hull as possible with hopefully none of the holes below the waterline. I really like the aluminum plates and long bolts. You would only need one every 16" or so and if they were in the middle of the collar that was glued on and above the waterline i'd feel pretty good. If there is a way to glue and resin a collar together the plates could even be incorporated into the collar and largely hidden. The plates and bolts would really serve to keep the collar from delaminating from the boat.
After thinking about this and writing all this out i think this has great promise but also sounds like a huge pain in the ass. I think i will proceed first with some flotation pods and do more research on foam and collar placement. Sorry for the rambling.

 

[Shaugh]

UV ray concerns:

PVC mesh fabric can be purchased with a very tight weave that allows zero UV to reach the foam:

https://www.fabricguru.com/p-sunbrella/acrylic-sling-chair-outdoor-fabric-18

Polystyrene insulation foam is very stable and inside those covers it would stay perfectly functional for 100 years in direct sun. I have boats that are over 10 years old that still looked brand new.

Outrigger stability when mounted to the boat concerns:

The fabric covers are very tight and compress the rigid foam. The PVC fabric is incredibly strong and will not stretch (which is why they use it for chair seats). I have seen zero tendency for the foam to move around once it's zipped up tight in the cover. Layers of the foam are glued together and once finished behave like block of plastic... (which is what it is..). At a width of only 8" This would not be a concern imo. You could easily glue the foam to the cover before zipping it up but that works against another nice feature which is ease of serviceability. Glue is a one way street....

The outrigger is mounted to the boat with aluminum bars that would be bolted every 24". When they were mounted and properly stretched between the bars, the outrigger would be nearly impossible to move more than about 1/4" in any direction. This is more than adequate stability imo, but we could beef up the mounting to include the through bolts and plates, although I think that method is ugly. Lastly you could also glue the outrigger to the side of the boat as part of the installation, but that again is not necessary imo.

Reverse Chine claims:

the reverse chine is simply a natural result of bolting a rectangle to an outward leaning side wall. It may have some small handling benefits, but at most normal speeds and conditions the effect would be minimal. On a 14' boat with a 25hp motor it would be a non issue imo, but it does provide a very clean edge that would reduce spray. The real handling benefit is in creating a boat that is functionally 16" wider than the current boat..

And of course the best benefit of all is cost... a pair of 12' outriggers could be made for about $300 cost of materials and sewing labor.

 

[Molokai]

This boat is not a collared boat but designed with the reverse chine as a design feature. It does seem to have some unigue dual hull benefits but for our application i think you are correct they minimal. I have read on some Australian boat forums there have been some negative handling results from the collar install.
[youtube]pXyk_QkuH-o[/youtube]

The hardware could be hidden if the foam block was glued together. Before gluing the last piece of the sandwich the plate could be hidden within that last piece. The rail system looks sturdy but it is also more through hull screws. Im curious about the pvc sunbrella fabric....do you think it could be bonded to the foam with epoxy resin? kind of like a surfboard?

 

[Shaugh]

I think we could also design a bumper rail that ran the length of the outrigger. this would allow for the bolts and would not look like a "garage solution" which is what they are selling for $1000 +...

Doing it that way we could eliminate the tunnels and bars... an inexpensive idea would be to split a 3" PVC pipe down the center and use each half as the bumper.

Like I say I think glue would be unnecessary... but a slightly flexible glue like simple silicone would probably work best...

The bumper idea is a good solution that should eliminate any worries about gluing imo...

 

[Shaugh]

Anybody who might want to try it can give me their dimensions and I'll create a fabric cutting diagram to calculate how many yards of fabric you will need.