Sponsons question

[biggs]

Are sponsons only for stability or do they also raise the max weight capacity of a boat?

Heres my problem, I just picked up a 10ft jon boat for a few shallow weedy bays and the max weight cap. is 245lbs. I weigh 160ish, the trolling motor battery is 55lbs and the motor is probably around 40lbs which equals 255lb and thats not even including gear etc.....

One of the previous owners built sponsons for the boat that fit perfectly to both sides to increase stability but I was wondering if they will raise max weight capacity as well?? Any way to increase max cap?

Maybe I will have to leave the motor at home and paddle! hope not though.

Thanks in advance.

[rugbyfisherman]

Hey Biggs,

I sold canoes and kayaks for a summer so I know a little bit about sponsons. From my knowledge sponsons are used solely for increasing stability. There is a guy in my area that custom makes them for kayak fishermen and I have actually paddled and fished out of one of his kayaks. On a kayak sponsons due actually make the boat sit higher in the water so technically they do increase the weight capacity although I would think the amount would be minimal - on your jon boat I would expect the effects to be substantially less.

If the sponsons have a massive volume they might increase your capacity by a few pounds. I think they might be a good idea, however, for general safety if you are going to be that close to the max capacity of the vessel.

Another option would be a more powerful electric to use as a dedicated motor. I have a friend that uses an aluminum mount across the gunwales of a canoe with a 55lb thrust minn-kota and he can produce a small wake!

[biggs]

Thanks man, I kind of figured they are for lateral stability only. I think the first outing with it I am going to just paddle to see how it feels then go from there. I only want to use the jon boat in a few small weedy bays around here so really paddling wouldn't be so bad........I am just happy I won't be on shore at these spots anymore!

I was trying to do the math yesterday to figure if the sponsons will help float the boat a bit more.
1 cubic foot of foam will float about 60lbs (1 cubic foot of air will support 62lbs).
the sponsons are around 5-6 cubic feet (they are not perfectly square) which would lead me to believe that it might be OK since with the sponsons attached I am going over the boats max cap. by 10-15lbs. BUT my math was never any good so this is a case of SAFETY FIRST!

Thanks again for the response rugbyfisherman

[rugbyfisherman]

No problem. I think it would be a good idea (like you said) to take it for a test without the motor. Just wait until the water warms up and take it out in a nice shallow area!