Tohatsu 9.8 on my Zodiac 285

lightning · 04 January 2012, 20:16

I have the opportunity to buy a Tohatsu 9.8 2-stroke engine

I have a Zodiac 2.8m SIB with a solid floor and air keel. At present I have a Mercury 6hp 4 stroke on it, and it's a good engine.
The boat will plane with two adults on board, achieving about 14mph on the GPS. However with three of us on board (rare) it won't plane.

The Tohatsu weighs the same (26kg) as my existing engine, and offers an extra 4hp. also it can be carried and stored at any angle. Is it a single or twin cylinder?

Would this be worth buying for my boat? I use it in various waters, from trolling on the canal to higher speeds on Scottish Lochs.

I was wondering if the Tohatsu would be more refined, as the Mercury is flat out when planing and also vibrates a bit through the tiller.

Will the Tohatsu 9.8 2 stroke sit at idle speed on the canal OK? And how is it for noise levels at lower speeds? On the canal we are generally at 2-4 mph which is about 1/4 throttle on the Mercury.

willk · 04 January 2012, 20:24

They don't like idling for too long and need the odd "blip" to keep them running. I'd imagine it would HAVE to be noisier than the 4 stroke. They're a refined enough unit at revs - I don't notice any big vibration at close to WOT. At low speeds, they're not overly loud.

The performance should improve, especially the time to plane (hole shot). However, the extra 4hp won't make a massive difference to your top speed, but might mean that you can plane with three, on calm water.

With a similar SIB, my max speed was 18kts, one up, sweet FA on board.

Go on - buy it - you know you want to!

Ribtecer · 04 January 2012, 20:46

If I where you I would, I bought one in the Autum and its great.

SIBer · 04 January 2012, 21:38

Details here
TOHATSU 9.8 HP 2-STROKE prices, specs, manuals and brochures.

Its a 2 cylinder and as its a 2 stroke you can lie it down anyway you like.
Its a bit noisy on low speeds but a bullet proof engine.

moonshadow · 04 January 2012, 22:28

Highly reccomend the 9.8 tohatsu,i have one from new and will probably never sell it,currently pushes my Avon 3.1 tender with jockey console easily on the plane with myself and the youngfella at about19/20 knts.

clydeoutboards · 05 January 2012, 14:47

Hi

As a dealer for these engines we have found no problems with them and are great value for money.

if you are comming up to the scottish lochs you can always bring it in a drink camerons naff coffee why we check it over but I doubt it will need it.

However if you are pottering on the canal at 1/4 or less throttle I would stick with a 4 stroke.

Dave

Max... · 05 January 2012, 15:17

I've got one so I guess I'm biased and agree with others here. Almost ridiculously simple engines to maintain and for the size very light. However, as others have said for canal pootling a 4 st may be better - running the Tohatsu at 2 - 4 mph it will be quiet enough - but up it to 6 - 8 (maximum displacement speed) it can get noisy.

WOT with 1.5 to 3 people on our Zodiac top speed varies but max is just over 17kts (20mph).

lightning · 05 January 2012, 19:08

Thanks for the advice.

It looks like the Tohatsu engine will not be ideal for the canal.

I think the best thing would be to have two engines, one for open water and a lightweight 4-stroke for the canal (maybe the Honda 2.5hp) which would be a fair bit lighter than my existing engine and plenty fast enough.

Max... · 05 January 2012, 20:58

Beware - I think the baby Honda is air-cooled and not so quiet.

mister p · 05 January 2012, 21:11

Very correct about the noise issue on the baby Honda

clydeoutboards · 06 January 2012, 08:08

Hi

i would hear the honda running before rulling it out, yes it is air cooled but this has been a plus and the noise never a problem when you hear other engines side by side.

The only downside for me is that Honda's always come with everything and the longest warranty but oh no. This engine comes in at 12.5kg for the short and 13.5 for the long but it does not come with a carrier/ shoulder bag! This is amazingly classed a an extra.

so as the mercury , mariner and Tohatsu's are the same for small engines the Tohatsu is also worth a look.

Poly · 06 January 2012, 13:27

Quote:

Originally Posted by clydeoutboards

i would hear the honda running before rulling it out, yes it is air cooled but this has been a plus and the noise never a problem when you hear other engines side by side.

I used to have a 2HP air cooled Honda and at full throttle it was at least as noisy as my 20HP Yamaha 2 stroke... ...its not a pleasant noise either - but there are some advantages for canal running such as not having to worry about weed / plastic bags blocking the cooling water intake. I imagine the plastic prob and centrifugal clutch would also go a long way to protecting the gearbox from a shopping trolley strike. On the other hand transportation / storage of 4 strokes is a pain and I found that between this and extreeme sensitivity to angle of orientation when topping up the oil (to get it level in the sight glass) it would smoke more than a 2 stoke until it had been running for a while.

The Tohatsu 9.8 is a well liked engine. The only real benefits I can see from a small 4 stroke would be: lighter weight - but the tohatsu is not that bad; better fuel economy - but its not going to be a huge difference in terms of total litres per annum, possibly less likely to foul plugs on the 4 stroke - although I think that is possibly exaggerated from the old days of premix, and "add a bit extra oil to be sure", its also not the end of the world in a canal. Does that justify it compared to having a second engine to insure, maintain, winterise, etc?

clydeoutboards · 06 January 2012, 15:21

Hay Palwart

when am I servicing the honda? that sounds far to noisey compared to the one we serviced last week.

Dave

ps you can always drop it off at my place and grab a coffee as I am only in gartcosh

Poly · 06 January 2012, 17:09

Dave,

I flogged the Honda a while back. It doesn't fit on the back of this boat beside my main engine so was no longer useful.

clydeoutboards · 06 January 2012, 22:39

you are still welcome to pop round for a coffee!

lightning · 06 June 2012, 08:58

Just thought I'd update this thread. I've used the Tohatsu 9.8 on my SIB and can report that it works fine at low speeds on the canal. We went out for about 3 hours at speeds of 2-4mph which is pretty low RPM.
The engine did not complain at all, and the noise it makes is just a fairly quiet humming, in my opinion no worse than my previous engine, a Mariner 6hp 4-stroke.
The Tohatsu has a rubber damped/mounted power head so vibrations are not transmitted to the tiller which is better than the Mariner, which made my hand go to sleep after a couple of hours.
At higher RPM the engine just hums and I imagine it will be easier on the ears when planing as well, not tested this on the canal of course.
I'm guessing that this is due to the Tohatsu being a twin cylinder engine as much as anything.
Oh and the fuel quantity in the tank hardly seemed to drop at all with 3 hours trolling.

hobnob · 07 June 2012, 23:32

Quote:

Originally Posted by lightning

Just thought I'd update this thread. I've used the Tohatsu 9.8 on my SIB and can report that it works fine at low speeds on the canal. We went out for about 3 hours at speeds of 2-4mph which is pretty low RPM.

I have used my Yamaha 8hp 2T twin on a Zodiac. Nearly always WOT after warm-up.

It's now powering a displacement boat with a finer pitch prop. Running 10-20% power. Am thinking about changing spark plugs to a different temperature range, to avoid oiling the plugs. Might be helpful if the oiling becomes an issue for you.

lightning · 08 June 2012, 08:51

I'll see how it goes, currently running in on 25/1 premix so it smokes a bit, should be better when I change to 50/1

lightning · 08 September 2014, 23:16

Two years down the line and still using the Tohatsu 9.8, which is currently fitted to my friend's Honwave SIB.

The boat is kept in Anglesey, at my friend's caravan site.

It is hard to fault this engine, in its' class. Just a shame it can no longer easily be bought new in the UK.

It started second time this year after being sat in the garage untouched all winter. I'd recommend this engine for any small boat where you have to manhandle the engine on and off.

Nightfisher · 10 September 2014, 09:25

Tohatso makes all smaller engines for Merc. I'm using a merc (2004) 9.9hp and it pushes my 14' Seamax beautifully. Have had two other adults onboard and it still reaches plane easily. I keep my type 31 Battery, 55 lb thrust electric and 6 gallon fuel tank at the front to balance weight making the boat jump on plain fast as well as keeping the bow down.