Shaft Length?

[chrishowden]

I am thinking of getting a 2.3hp honda outboard and not sure what shaft length will i need to fit on the back of my avon adventure 450

[Downhilldai]

Main motor or auxiliary?

[spartacus]

I'd have thought it would be long shaft. Are you intending to mount it on the transom, or have it stored elsewhere onboard?

[Hightower]

If I were you, I'd consider a more powerful outboard. My old 5m RIB with a 2.5hp Aux motor was useless and couldn't even manage a straight course in small tides and wind conditions.

[spartacus]

Originally Posted by Hightower

If I were you, I'd consider a more powerful outboard. My old 5m RIB with a 2.5hp Aux motor was useless and couldn't even manage a straight course in small tides and wind conditions.

Agree with that. A Yamaha 2-stroke 4hp would be ideal. Like rocking horse poo to find though.

[Downhilldai]

I use a 3.3hp Merc auxiliary on a 4.7m Searider and it's ok. A larger outboard would need a bracket, as there's only just enough room on the transom for the 3.3hp, 'cos the boat has an A-frame.

[chrishowden]

what size of outboard would you recomend then

[MOS]

4hp should be plenty...

the yamaha two-stroke 5hp is the same engine as the 4hp, as in weight and size.

For shaft size, I would measure from the transom down... Obviously I am going to presume the aux isn't going to be in the middle of the transom and as such doesn't need to be as long shafted as the main engine?

The Yam 4/5hp two-stroke shaft lengths are:

S - 444mm L - 571mm

www.mobileoutboardservices.com

[chrishowden]

would i get away with a 2.3 honda. I have a budget of £550 and would pefer it to be new if possible

[Poly]

Chris,

Not sure how far you are planning to venture in the new boat, but assuming you are looking at the Firth of Forth West of Berwick then I'd have thought the Honda 2.3 would give you enough power... it won't get you anywhere fast, and it might only get you to some shoreline somewhere that you can get a bus home, but thats better than calling out the lifeboat!

However if I had £550 to spend I would go for a bigger second hand model if it would fit on the transom.

Finally your boat is not actually long enough for the Honda 2.3 - you won't be able to get far enough away from the noise of the air cooled engine running at full throttle to bear using if for any length of time.

[chrishowden]

so what outboard do you recommend then

[Poly]

Originally Posted by chrishowden

so what outboard do you recommend then

IIRC only the Honda 2/2.3 are air cooled - so almost any other outboard would be better on the ear! They are also quite "wide" so if you can fit one of them you'd probably get a 3.3 or bigger of another type on their. If you are not storing it on the transom all the time then i'd go 2 stroke so you don't need to worry about which way round to lie it down. More horses is always going to be more reassuring!

[9D280]

There is an engine out there that I think I'm safe in saying has carried almost every manufacturer's livery at some point in it's production history. - It's the square plastic case with a vertical throttle lever on the front. Nice & slim, and some (Def. Tohatsu & maybe Mariner or Suz) badged ones were 3.5HP. They have been sold as low as 1.5 Hp (presumably for tenders & canoes). Weigh about 12Kg fully fuelled, F/N gears and are slim enoguh to fit on an SR4 transom.
http://www.tohatsu-outboards.com/tohatsu-3-5-HP.htm



Other option if you don't mind going a bit older is the Johson / Evenrude twin pot 4. They are also relatively slim, weigh about 13 KG fully fuelled and have the advantage that it will still run if you loose a cylinder. Newer ones had a F/N select, otherwise it's a permanently in gear Stop / go, so need to make sure you are pointing roughly the right way when and / or have a plan before it fires. I've got one as my Aux, and it took me the entire N/S leg of Loch etivce last summer during the 70 Wild miles event. Used it because it was better that at 3/4 throttle than the main at ticjkover oiling up at canoe speed! I think Pol has the 2Hp single cyl version as his Aux. Plenty of them secondhand.
http://www.old-omc.de/e_1973/seite_18_19.jpg
http://www.old-omc.de/e_1972/seite_04_05.jpg

Other option is two of the first one I mentioned & have a 2Hp each side of the main!

[chrishowden]

thanks for the advice can you look out for second hand outboards if you see any good ones thanks
chris

[Hightower]

I was going to mention the Tohatsu too

£600 should buy you a new 3.5hp, do a google shopping search

[chrishowden]

thanks for the advice sounds good will check it out

[ADI]

I would buy a 3.5hp Mercury / Mariner longshaft fourstroke

[spartacus]

Originally Posted by Hightower

I was going to mention the Tohatsu too

£600 should buy you a new 3.5hp, do a google shopping search

The Tohatsu 3.5hp is a cracking little engine. I bought one of the last 2-strokes in 2008 from Extreme Marine as an auxilliary.
My only criticism is the transom bracket and tilt push bolt isn't robust enough. It's fine if it was your main engine on a little tender, but not as an auxilliary, bouncing around. This needs to be secured while underway (under tension with ratchet strap), or there's a good chance it will disintegrate!

[9D280]

Originally Posted by spartacus

It's fine if it was your main engine on a little tender, but not as an auxilliary, bouncing around. This needs to be secured while underway (under tension with ratchet strap), or there's a good chance it will disintegrate!

That could be said of most small engines........

Other thing to remember - Longshaft on the low Horsepower engines isn't the same long as the "big" ones. I forget where the cut- off is, but below about 20 Hp I would use actual measurements. Chances are you'll need a long shaft - when I had a short shaft as an aux I had to be sat on the toob beside it to keep the prop in the water.