9.8 or 15 outboard dilemma

[blootac]

I've currently got an Avon 310, old style with ply floorboards and inflatable keel. It's rated for 10hp max and is very very rarely used with <2 people.

It's currently got a 9.9 Johnson on the back that is on it's way out and needs replacing.

My dilemma is that the boat will likely be replaced in a year or two's time, at which point I'll be looking to get a 3.8m.

I'm looking at the Tohatsu's, do I get the 9.8 which has the advantage of being very light and just accept that I'll have to get shot when I replace the boat,
OR
do I take the risk and get the 15, don't use it at full throttle but actually have something that I can use on future boats.

With the current 9.9 it won't plane with 2 people when facing the wind and when not facing the wind everyone has to move forwards (side effect of it's short size I realise), but when it is planing it's getting 18-19 knots. I'm hoping that with the 15 that planing would no longer be an issue. Or am I just experiencing old age and some of the horses have escaped from the Johnson and the new 9.8 would be a different beast? or is it simply that it's too short?

So my question to you all is, what would you do? Buy the £150 cheaper, smaller model and then replace in 2 years time, or get a 1/3 larger engine than the boat is rated for, don't use it fully (but it's still there if you get into trouble) but keep it long term.

Thanks

[Fenlander]

A 10hp should plane your Avon 2 up unless you are heavy or carry loads of other kit. We had a Tohatsu 9.8 on an older Zodiac 3.1 with plywood floors and that would plane with 2 adults or 1 adult and 2 small teens. They are the ideal motor for your Avon.

Perhaps the old Johnson is tired?

If you buy a Tohatsu 9.8 this time of year you should be able to sell it on at a profit (or lose nothing) one spring/summer when you need to upgrade.

Having said that there is sense in finding the right 15hp now to save the hassle of changing in the future. In truth assuming your Avon is still sound the extra power isn't likely to make it fall apart and as it's rated to a 10hp the weight will be fine as nearly all 15s weigh the same as 9.9s.

[blootac]

Thanks Fenlander,
That's very much the conclusion I'd come to.
The Tohatsu 9.8 is very light because it's an upgraded 8, whereas the 15 is a crippled 20.
The dry weight for the 9.8 is 37KG vs 52KG for the 15.

[Fenlander]

Where are you getting those weights from... are these new 4-strokes? All my comments related to used 2-strokes.

[blootac]

The tohatsu website, and yes, new 4 strokes
Tohatsu 9.8hp outboard
Tohatsu 15hp 4-stroke outboard

[blootac]

Ah, sorry, I didn't specify in my original post. I'm looking to replace with a brand new 4 stroke (only as new 2 strokes aren't available new anymore)

[Fenlander]

Oh well that 15hp Tohatsu is a terrible power to weight ratio for a small sib and really too heavy to lug about. A 20hp Honda 4-stroke weighs 6kg less.

And the 9.8 4-stroke weighs more than a 15hp used 2-stroke.

I really can't get my head round putting an expensive heavy 4-stroke on a small SIB.

[Max...]

You won't find much support for 4 strokes on SIB's on Ribnet - we all use 2 strokes - the 15 Mariner/Mercury is the perfect SIB engine being the lightest 15 and very user friendly. Smaller and lighter is the Tohatsu 9.8 but obviously what you gain in weight and fuel consumption you lose in oommmppphhh.

[blootac]

The move to the 4 stroke was purely to do with the perception of a more reliable engine (despite being more complicated) plus being backed by a warranty and further complicated by the low availability of young(ish) and/or well maintained 2 strokes.

I agree that the 2 strokes are preferable, especially as they won't empty a litre of oil into your car boot when put on their wrong side!

Looks like I'll have to keep looking for 2 strokes!

Thank you both.

[Nick Hearne]

I would forget a 4st and get a nice 15hp 2st not the best example but something like this Yamaha 15Hp Outboard 2004 Short Shaft | eBay 36kg nice and quiet too for a 2st

[Fenlander]

I wonder which 3.8 SIB you have your eye on for an upgrade blootac?

[spartacus]

Yammie 15hp 4-stroke here: Yamaha F15CES Remote - Pre-Owned | www.penninemarine.com

Yammie 15hp 2-stroke long shaft here: Details of OB100187 - Yamaha 15hp long shaft

[blootac]

Fenlander,
I've got my eye on a Highfield CL380, not quite a SIB in that it won't collapse but still has wheels so can be wheeled up a beach, plus the 15 deg deadrise should make quite an improvement to my flat floor and is quite a bit cheaper than the OM420, although the 420 is a much more capable boat...
CL 380 - Highfield UK

I know the recommended for the CL380 is 20hp but I thought that I could probably get away with a 15 for the short term.

[John Kennett]

I've said it before, but I reckon that lightweight aluminium RIBs could be a really good alternative to SIBs for anyone who doesn't need to deflate the boat to store it.

It would be very interesting to put one of these head to head with an Aerotec sometime.

[Fenlander]

>>> I reckon that lightweight aluminium RIBs could be a really good alternative to SIBs for anyone who doesn't need to deflate the boat to store it.

Agreed. In the past we've had trailed 13ft - 17ft boats but currently the need for compact storage in the garage and suitability of not having to tow on long holiday trips makes a SIB ideal.

But should circumstances change a small light RIB with 20hp max would be of great interest. Even if you have to trail to your destination the ability to use SIB type transom wheels to launch in tight places where a car and trailer might struggle is an interesting option.

We were on the pontoon last year when a couple in their 50s wheeled one of these down and launched it smoothly straight off the side of the pontoon into the sea. It was so light and easy to handle (a 3.4 I think).

We chatted to them and they were really pleased with it, if I remember correctly they'd imported it specially from Australia having seen it at the boat show.

[blootac]

Yeah it's a compromise.
I've grown up with Avon Rovers R330 and R310 but I slipped three discs in my neck in May when I lifted the outboard awkwardly out of the car so I've decided to get a small trailer (considering an indespension coaster micro, which is big enough to hold the CL380), not to launch with but to get to the beach with so I no longer have to lift anything.

Given that I'm now limiting myself to having a trailer, the huge advantage of a SIB is no longer applicable, so I'm left contemplating a RIB like the OM420 which still has a low draft (30cm ish apparently) or the CL380 which is a lot lighter (meaning smaller outboard = less fuel etc) and can still be dragged up and down a beach by a single person. but that compromise then comes with no fixed vhf/plotter/gadgets and no cross channel attempts!

[Fenlander]

And of course my advice re outboards was all SIB based... not quite so appropriate if you are going to a small RIB with trailer.

Having said that where there are two different outputs for the same weight (i.e. 15 vs 20) I'd always go for the higher output.

[Nick Hearne]

Originally Posted by John Kennett

I've said it before, but I reckon that lightweight aluminium RIBs could be a really good alternative to SIBs for anyone who doesn't need to deflate the boat to store it.

It would be very interesting to put one of these head to head with an Aerotec sometime.

I like the look of the Ribeye aluminum tender ribs and my brother in law has a Brig 360 with a 30 hp 2 St on it and I can only just out run it with my Sr4 with the 50hp 2St on it
But it is hard going and you have to be young with balls of steel to run it flat out in anything but flat calm conditions! Still got to be better than a Sib kept on a trailer though!

[Max...]

If you are always trailering and leave the engine on and generally use a slip then a baby-RIB all the way I reckon.

[Landlockedpirate]

The problem you have is that until you buy your new boat, the engine will live on an older Avon 310. You are not going to get an engine that will do both jobs brilliantly.

Fenlander has the right idea, buy the best Tohatsu 9.8 2 stroke you can find and use that on the current sib.When its time to buy the mini rib, sell the Tohatsu for the same money and buy an engine that suits your new boat.