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PVC Sponsons/Flotation on a john boat?
Posted: May 31st, 2013, 2:09 pm
by bman
I have a friend considering this...
He has a limited budget and is trying to boost the safety on his 14foot john.

Here is a youtube video where he got the idea:
https://www.youtube.com/watch?v=ANoSwwITLXY[/video]
I can remember canoes with foam strips down the side that would do the same thing... looks like it may work.
According to Google 1 cubic foot of air will support 62 lbs
4" pipe 10 feet long supports 186lbs- or a total of 372lbs for both sponsons
6" pipe 10 feet long supports 487lbs - or a total of 974lbs for both sponsons.
Here is the area calculator if you want to play with the numbers
http://ncalculators.com/area-volume/...calculator.htm
What do you guys think?
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Re: PVC Sponsons/Flotation on a john boat?
Posted: May 31st, 2013, 2:15 pm
by slowroller
Saw a guy leaving the lighthouse channel rigged up like that about 2 months ago. Said it was his maiden voyage.
Re: PVC Sponsons/Flotation on a john boat?
Posted: May 31st, 2013, 2:19 pm
by robbankston
Seems reasonable....
Re: PVC Sponsons/Flotation on a john boat?
Posted: May 31st, 2013, 2:20 pm
by bman
slowroller wrote:Saw a guy leaving the lighthouse channel rigged up like that about 2 months ago. Said it was his maiden voyage.
Did he come back?
Re: PVC Sponsons/Flotation on a john boat?
Posted: May 31st, 2013, 2:23 pm
by captkeyser
and it will help reduce spray. I LOVE IT! Great idea!!!
Re: PVC Sponsons/Flotation on a john boat?
Posted: May 31st, 2013, 2:34 pm
by Flint River Pirate
That is a very clever idea
Re: PVC Sponsons/Flotation on a john boat?
Posted: May 31st, 2013, 2:44 pm
by slowroller
I told him good luck and never saw him again!!
Re: PVC Sponsons/Flotation on a john boat?
Posted: May 31st, 2013, 3:08 pm
by guthooked
Fine example of redneck engineering.
Re: PVC Sponsons/Flotation on a john boat?
Posted: May 31st, 2013, 3:38 pm
by Badbagger
Barry, read something similar on tinboats a short while ago.
http://www.tinboats.net/forum/viewtopic.php?f=3&t=30656
Re: PVC Sponsons/Flotation on a john boat?
Posted: May 31st, 2013, 3:59 pm
by rockyg
Not quite as pretty as a new Hell's Bay.....but it just might work. There is something similar you can buy for a Canoe/Kayak that acts like an outrigger for extra stability.
Hope it works for your friend.

Re: PVC Sponsons/Flotation on a john boat?
Posted: May 31st, 2013, 5:07 pm
by charlie tuna
Hope he has some big washers on that all thread, because if he ever gets in a good chop, the all thread is going to eat a hole in the side of his boat real fast -- but then it wont sink, just fill up with water!!

Re: PVC Sponsons/Flotation on a john boat?
Posted: May 31st, 2013, 9:48 pm
by Steve Stinson
I am not sure its needed. If you don't puncture the sides of the compartments where the floatation foam is in your aluminum boat, and your foam is not waterlogged, it should support you enough to keep your boat gunnels level with the water.
I sunk my boat last year after hitting a rock out near Black Rock. I put a 1.5 inch x 18 inch gash in the bottom just forward of the center console. I managed to keep the motor running and move at about 3 mph for 4 miles back to the lighthouse ramp. The foam in my old hull was the only thing that kept me level with the waters surface. Having survived all that, I would suggest the following for small aluminum boats-
1. Make sure you can get your fuel tanks someplace where you can keep them vented, but not get water in them. If you seal them in a compartment, or use a built in tank you will end up with water in your fuel supply and your motor will shut down. I move mine up on top of the casting deck to keep running.
2. Same for your batteries. Be sure you have enough cable to put your battery on top of a deck or seat. if it grounds to the bottom of a deck and you have fuel leaking in your boat you will lose your electrical power and have a fire hazard. My battery grounded to the bottom of my rear casting deck and melted both posts. I still don't know why it kept working. (A 12 volt battery submerged in fresh water will keep working, but in saltwater, it will go dead immediately).
3. Keep some kind of packing and some duct tape on board. If I had thought to stuff a rag or part of a life jacket in the split on my hull, then tape over it, I may have been able to pump enough water out to run back in.
4. Keep a dive mask or swim goggles on board so you can see to find the damage. We checked the perimeter of my hull and the outboard, which were both fine in my incident.
5. Keep a dry box handy. Once you know you have serious problems, put all your cell phones, portable radios, flares, etc. in the dry box so that you have the ability to call for help for as long as possible.
6. Keep your bilge pumps working. If you don't have one, put one in. Heck, put 2 in.
Good luck, and watch out for those roaming rock piles out there...
Re: PVC Sponsons/Flotation on a john boat?
Posted: May 31st, 2013, 9:56 pm
by Flint River Pirate
I forgot that happened Steve! I'm glad you made it through that ordeal.
Re: PVC Sponsons/Flotation on a john boat?
Posted: June 1st, 2013, 11:52 am
by Redbelly
Steve how is your new boat workin out?
Re: PVC Sponsons/Flotation on a john boat?
Posted: June 1st, 2013, 2:54 pm
by RodBow
seems like anything other than a very gradual turn would be an issue..