outboard speed?

[mirssant]

Originally Posted by jason22

Hi All

Thank you for your info , certainly got me thinking on the size of rib and out board to go for.
Would any one recommend ebay for a cheap rib or any were else?

My avon s400 is 13 foot long i used with an evinrude 40 hp for 15 years, now i use a mariner 15 hp 2 strokes and i dont feel to much diferent about de boat maxium speed of course less power ,you must considerate the use you want, sib's are desing for a top maxium speed

[MikeP]

Hmm, I've noticed that thinking about things like outboard engine sizes can start expensive speculation...

We went down to Bristol Boats today to pick up our 4HP from its first service and had a chat about bigger outboards. She had a 9.5HP Tohatsu four stroke down there which is apparently a lightweight version - but it comes in at 37Kg! It also looks like you get a big jump in size at that HP which makes me wonder how our little 3.1m SIB would cope (and look) with such a monster on the back.

I'm a bit dubious about 2 stroke, although obviously a lot of people have had an awful lot of enjoyable SIBing hours with 2 stroke engines before the emission regs changed, so maybe I'm just being picky. However, what is the chance of getting hold of a nice example of the 9.5HP Tohatsu or similar in a 2 stroke version... ?

The annoying thing is that the 4HP is perfect for our current jaunts on river/floating harbour and canal, where the speed limit stops you anyway. So my sudden thoughts about a bigger engine are all to do with a presumed future of SIBing in speed-limit-less areas.

Of course, having just come back from a rain-soaked holiday in Scotland doesn't help as every wee loch that we passed had me thinking how nice it would be to be out there in our SIB enjoying the water.

<sigh>

[Locozodiac]

Originally Posted by MikeP

wonder how our little 3.1m SIB would cope (and look) with such a monster on the back.

My first sib was a Zodiac 310 with a 37 Kg Evi 15 HP and performed very well with 2/3mates, so a 9.8 -4 strokes will be ok for your sib. If in need of more power, try to get a Tohatsu 2 strokes 9.8/9.9/15 HP if available.

Happy Sibbing

[Fenlander]

Mike,

Our 2006 Tohatsu 9.8 2-stroke weighs just 2kg more than your 4hp Mariner with a very similar physical bulk. It will troll for hours at low speed with no oiling, using a quality oil we never notice smoke (unless you start it in the shed in a water tub), it uses very little fuel and has less parts to go wrong than a 4-stroke, is quiet and very easy to start.



So for your river use to all intents there are no downsides compared to yours... but get out onto the open sea or lochs and it will carry you about at up to 16-19 mph and allow a greater ability to pick your way through the waves if it gets rough.

The fun per lb ratio is very high!

David

[hobnob]

Originally Posted by Fenlander

is quiet and very easy to start.
David

Biggest difference for noise is single versus twin cylinder. My 2-stroke twin (Yam 8hp) is lovely and quiet at idle.

[MikeP]

Ahhh, the legendary, or - in my case mythical - Tohatsu 9.8 HP two stroke makes an appearance in this thread.

I think that would be the ideal solution, but actually *getting* a decent one seems to be the problem.

In the meantime, I have retired to the gym to start lifting 37KG weights.

[willfinch36]

When I was younger ( im 19 now)

Had a AVON Redstart with a 4HP, that would do 12 knots.

Then a Valiant 3.80 with a 25HP that would do 27 knots.

Now a Valiant 5.20 with a 70hp that will do 33Knots.

[lightning]

One thing I have found is that there is often a 4hp limit on lakes/rivers, and above that you have to pay a much higher tax to take your boat on them. I've got the Mercury 6hp (looks the same as the 4hp) and had this issue in Chester on the river Dee.
Fortunately in this case I was able to convert the engine to a 4hp by replacing the "6" on the cover with a stick on number "4" from the local hardware store....

[phillnjack]

My daughters have a meastral sib about 9ft 6in long with a mercury 4hp 2stroke circa 1991.
A few years back we took it with us when friends went watersking of the solent.
When the skier dropped a ski i was there to pick it up straight away.
Everyone was suprised to see this little boat keeping up with a speedboat teaching some to mono ski.
This little rig will do 16mph on the sea, and about 14 on the inland waterways.
with 3 small children it still stays on the plane.
Now days i weigh just over 18 stone and the rig will just get on the plane, but with a struggle.
Not bad for just 4hp.

Now im about to see what a 30hp 2 stroke will do on the back of my latest boat, a avon s400.




phill