How Fast should my Honwave go?

[Jamie_B]

I have a Honwave T40 and a 4 stroke Honda 20 hp. Using the speedo on my iphone it showed 20mph or 17.4 knots , we were on the Thames and it was flat and calm. But to me it sounds like the engine isn’t running at full tilt, please bear in mind:

A. I’m a novice
B. There was two of us combined weight about 38 stone
C. Boat and outboard are 6 years old
D. Not sure how accurate iphone god speed test is

[Fenlander]

Jamie that's in the right ball park as you have a heavy large SIB and well fed crew! Perhaps a little low maybe though?

First thing to check is if you are 100% up to pressure on tubes and keel using a gauge you trust and rechecked after 10mins on the water.

I always check under the OB hood to make sure the twist throttle opens the carb fully.

Prop pitch is worth checking...I'd guess a 10" would suit you.

However it's impossible to tell if you are getting the best from the outfit without knowing engine revs so you need a cheap universal rev counter and to give us some revs vs speed readings. See this thread for guidance on a tach...

http://www.rib.net/forum/f36/best-ti...ype-71268.html

[Max...]

Does not sound far off if at all for a couple of heavy crew members. Weight and distribution affects things greatly in these little low powered rubber boats. As Fenlander says - double check pressure and you will need a tach to see if you're reaching max revs at WOT. Trim on SIB's is pretty much always best in the middle for the majority but check this too.

But again 17.5 is probably what you should expect - heavy boat and crew and 20hp.
You can usually gain/lose a knot or more by trying different weight distribution though.

[jeffstevens763@g]

What size prop you got on?

[Mikefule]

It sounds about right. Indeed, for insurance purposes, I think you will find it does not exceed 20 mph.

[Lee1]

A 4 stroke will not sound like a 2 stroke at WOT the speed your getting is about right for the weight onboard and the 4 stroke engine used, If health and safety and/or insurance wasn't an issue for you I would suggest using a 25-30hp 2 stroke! Otherwise try to spread the weight over the whole boat and make sure it's fully inflated.

[Safetyrib23]

Will my honwave t40 handle a mariner 40hp outboard weighing 72kg

[Fenlander]

Welcome to the forum.

That’s double the makers hp so unwise to me. I’m not sure re the weight spec for the Honwave but even a heavy old school 20hp was around 50kg so you’d be 50% over that weight.

Why a 40hp, do you already have that outboard?

[Safetyrib23]

Yes already have a 40hp

[Fenlander]

And do you already have the T40?

[chipko]

Seem to recall the T40 is rated to 30hp. There's probably a max motor weight on the transom plate as well, if that's over 72kg then probably worth a punt if a short shaft.

Our T38 was plated at 25hp and 83kg max weight.

[Fenlander]

Hmm seems Honwave have modified their outboard advice on the later models. The current T40 is rated to just 20hp same as the T35 and the T38 is now rated 20hp too. I remember Zodiac dropping some of their leisure range by 5hp a few years back at a model change point.

I didn’t find an online source that gave the advised OB weights though.

[Fenlander]

A little bit of research indicates the older T40 was indeed rated to 30hp and 70kg.

[smallribber]

Originally Posted by Fenlander

Welcome to the forum.

That’s double the makers hp so unwise to me. I’m not sure re the weight spec for the Honwave but even a heavy old school 20hp was around 50kg so you’d be 50% over that weight.

Why a 40hp, do you already have that outboard?

The website says 20 hp but the plate on the Transom says 30 HP. But 40 would deffo be too much. I know people who have a 30 on them and they feel that is too much