How fast can you go with 3.5hp (on water)?

[dancrane]

Thank you, that's very useful!

I had a feeling it wasn't purely a matter of weight and output per kilo.

I suppose in a light boat, if at top speed with one engine, you're going as fast as the propeller is pitched for, then another similar engine (or another three) turning the same props at the same speed, won't move the boat much faster. It might increase the barge-pull effect but not the speed.

How skinny is your planing friend? It'd encourage my weight loss if I knew.

 

[Rappey]

Hes a stick insect. I would be surprised if he is close to 60kg..
My inflatable used to plane with me. i posted a while back about this wondering what i can do to get just a little more power to get on the plane, suggesting my tohatsu has probably lost a little power over time. The reply was not to do anything to the outboard but to diet and get back to the weight i was when it planed Guess thats the harsh reality.

 

[billskip]

if at top speed with one engine, you're going as fast as the propeller is pitched for, then another similar engine (or another three) turning the same props at the same speed, won't move the boat much faster.

That's about the size of it.....but...it would possibly give you wriggle room to go over pitch....

 

[Hot Property]

I've had a selection of inflatables from a Redcrest to a Honwave.

Thee Honwave was 3.2 meters long with an inflatable V floor. Fitted with a 15 EFI Mariner it would top out at 19 knots on flat water. The floor would start to deform which limits the speed.

Same engine on an Avon 3.1 rib gives 22 knots.

My brother has a similar V hull so. and with my 3.5 Mercury 4 stroke can just get on the plane at about 11 knots.

A bracket to hold a 3.5 tohatsu 2 stroke on a paddle board would be fun to try out. I would ratchet strap a seat so I could sit for better stability.

In the video the guy was unstable and couldn't put the full 6.5 HP into effect....

No kill cord but it was in Australia

 

[Iliade]

I have a vague memory of a 1960s/70s BBC program about a UK version of these hydroplanes, but with less top hamper, even smaller motors, and the kids lying down?

We had a water-jet longboard back in the 1990s, but that took something like 15hp to get up on the plane.