20hp Honda on Basstender 11.3

[Redheeler45]

A few years back I had a Basstender 11.3 with a 15HP Mercury, the coastguard plate in that boat said it was rated for a 15HP motor. I ended up having to sell that boat. Recently I purchased another Basstender 11.3 just like the one I previously had, I believe it is a few years older because the coast guard plate on this boat says 10HP motor even though this boat seems identical to my previous one. I wanted to put a 15HP Honda on this boat because I liked the 15HP motor I had on the previous one. Looking online I found a 20HP Honda for less than most 15HP ones go for. Would it be an issue to put a 20HP motor on it instead of a 15HP since they weigh the same? I know that would be twice the horsepower the tag says this boat is rated for but my previous identical boat was rated for 15HP so would this 20HP really be a problem?

 

[briangcc]

To get to that higher horsepower rating on your first boat, the manufacturer may have used different materials and/or strengthened the hull/transom to accept more power. The older boat probably doesn't have those design changes.

So to answer the question, I wouldn't put double the recommended HP on a boat. You may be cited on the water for exceeding capacity. You may be opening yourself up for legal issues in the case of an accident. You may have issues when you crack open the transom and the boat flexes.

I wouldn't exceed the label. But that's me not wanting to open myself up to being liable for exceeding manufacturer specs.

 

[Redheeler45]

To get to that higher horsepower rating on your first boat, the manufacturer may have used different materials and/or strengthened the hull/transom to accept more power. The older boat probably doesn't have those design changes.

So to answer the question, I wouldn't put double the recommended HP on a boat. You may be cited on the water for exceeding capacity. You may be opening yourself up for legal issues in the case of an accident. You may have issues when you crack open the transom and the boat flexes.

I wouldn't exceed the label. But that's me not wanting to open myself up to being liable for exceeding manufacturer specs.

Yeah that makes sense, thanks for the reply.

 

[flashback]

Other than the legal liability I'd go for it! It would be quick...

 

[Redheeler45]

Other than the legal liability I'd go for it! It would be quick...

I just wish I knew if they did anything to beef up the transome on the ones rated for 10HP vs 15HP. Every teardown video I’ve ever seen of a Basstender 11.3 looks the exact same on the inside.

 

[airshot]

Just the thickness of materials would make a big difference in strength but not in apoearance.

 

[QBhoy]

May not apply…but those wee Honda engines that size are fairly heavy. Not sure what age your boat is..but some older boats have their rating with a lighter 2 stroke in mind. Also, most often..with boats that size and length…an engine that’s too heavy can absolutely ruin the way it handles and performs. Too much weight at the back end can often mean that it may even not perform as well as it might with a 10hp 2 stroke on it. Just with the dynamics of a short planing area on a small hull…and too much weight aft. I once had a small 2.7m rib…with a 15hp on it..it wouldn’t plane with 2 people in it. But it would with an 8hp. Just wasn’t able to spread the weight equally enough over its short surface/planing area of that small hull.

 

[Redheeler45]

May not apply…but those wee Honda engines that size are fairly heavy. Not sure what age your boat is..but some older boats have their rating with a lighter 2 stroke in mind. Also, most often..with boats that size and length…an engine that’s too heavy can absolutely ruin the way it handles and performs. Too much weight at the back end can often mean that it may even not perform as well as it might with a 10hp 2 stroke on it. Just with the dynamics of a short planing area on a small hull…and too much weight aft. I once had a small 2.7m rib…with a 15hp on it..it wouldn’t plane with 2 people in it. But it would with an 8hp. Just wasn’t able to spread the weight equally enough over its short surface/planing area of that small hull.

That's good to know. My old Basstender had a 15hp 4-stroke that weighed 99lbs according to the specs online, and a 15hp or 20hp Honda weighs 104lbs. My old Basstender performed great with that 15hp mercury, this new one has a 8hp 2 stroke and it pushes through the water pretty slow compared to that 15hp my other boat had.

 

[Scott Danforth]

Is the 8hp getting full RPM?

 

[Redheeler45]

Is the 8hp getting full RPM?

Seems to be.

 

[Scott Danforth]

Seems to be.

did you confirm with a tach?

 

[Redheeler45]

No, I don't have one to check the RPM with.