exceeding inflatable outboard hp rating

[ausnp84]

Originally Posted by Cadence

I think you are overthinking it. The boat was designed for a specific HP, why not stick with that. It's nit a rib.

That’s true - it’s not a rib, but that extra 2-4hp could be the difference between getting to shore relatively dry on the plane, or bouncing through chop and getting wet... I’m just curious whether that extra hp could push the boat outside it’s designed speed envelope.

Sounds like a spot of real world testing is needed on this one😁

N

[s/v Jedi]

Originally Posted by ausnp84

That’s true - it’s not a rib, but that extra 2-4hp could be the difference between getting to shore relatively dry on the plane, or bouncing through chop and getting wet... I’m just curious whether that extra hp could push the boat outside it’s designed speed envelope.

Sounds like a spot of real world testing is needed on this one😁

N

Sounds like you need a larger dinghy that can take a bigger outboard

[Fuss]

Originally Posted by mikedefieslife

Stolen from a UK forum. 25hp on a 2.1m dinghy. The guy says it does nearly 9 knts at just over tickover and over 24 knts with half throttle.

Obviously this is extreme but does look like fun.

As to insurance, normally in the UK possibly the EU, insurance would have to pay up to a third party even if you breach their terms. They may or may not try to get some of that back from you. However, they would only likely be successful if your breach or negligence was the reason for the accident.

There are hundreds of cases like this with modified cars and bikes in the UK. If the modification wasn't the cause or a contributable factor in the accident then you are off the hook.

If you get an engine problem with this setup and you lean over the motor to fix it, the dingy will flip as there is not enough boyancy behind the transom.

[capn_billl]

Originally Posted by ausnp84

That’s true - it’s not a rib, but that extra 2-4hp could be the difference between getting to shore relatively dry on the plane, or bouncing through chop and getting wet... I’m just curious whether that extra hp could push the boat outside it’s designed speed envelope.

Sounds like a spot of real world testing is needed on this one😁

N

My experience both with overpowered dinghies, and not is the extra HP will be little help.

Can you get by with overpowered?

Yes.

Is it safe"

no.

I found with a 10HP on a dinghy rated for 6HP, I had to be very cautious on the gas, or it would flip.

The extra HP added very little to speed because the weight put the stern too low, (to plane you need to climb the bow wave, harder to do when you are squatting).

Even with me & gas tank in bow, it sat low in the stern, and the bow tended to buck under acceleration.

A couple feet longer boat, and the 10 HP worked fine.

A short inflatable just didn't have the mass to handle the added torque.

[ausnp84]

Originally Posted by capn_billl

My experience both with overpowered dinghies, and not is the extra HP will be little help.

Can you get by with overpowered?

Yes.

Is it safe"

no.

I found with a 10HP on a dinghy rated for 6HP, I had to be very cautious on the gas, or it would flip.

The extra HP added very little to speed because the weight put the stern too low, (to plane you need to climb the bow wave, harder to do when you are squatting).

Even with me & gas tank in bow, it sat low in the stern, and the bow tended to buck under acceleration.

A couple feet longer boat, and the 10 HP worked fine.

A short inflatable just didn't have the mass to handle the added torque.

Yep fair call. I buddy boated with someone who had a 2.7m and an 8hp, which worked quite well as a combo. Our current 2.7m is rated for a 6 and we’ll probably go for an 8 - the engines weigh almost the same and that extra hp will definitely help. Anything above that and the outboard weight / fuel burn just won’t be worth it.

N