Hi people
First post on here, looking for some advice on a replacement outboard for my latest project. Felix the catamaran is a 25ft bridgedeck cat and she has an old Tohatsu 9.9 mounted in the centre with remote controls.

The engine has some pretty serious looking corrosion and is likely to be terminal. I would like to replace it with a brand new motor if the budget allows but I am not sure what would be an equivalent model? And who would be a recommended dealer around the Pittwater area?

It would have to be electric start and have the remote controls as per the previous unit. And it must not weigh more than the last one which I think was 42kg based on internet searches. I'll double check it on the scales tonight.

Any suggestions?? Thanks!!

www.tohatsu.com.au/content/m98b for a 2 stroke
or
www.tohatsu.com.au/content/mfs98a3 for a 4 stroke

if you have the room and want a bit more kick try

www.tohatsu.com.au/content/mfs20c


How does it handle with the outboard placed midship ?

Oh and does anyone have any thoughts about 2 stroke vs 4 stroke?

I was was thinking of switching from 2 stroke to 4 stroke if they are quieter but is there any downside to making the switch?

I would not touch another Tohatsu. I had a 9.9hp which was well looked after, flushed, washed down and stored in a shed. Even being looked after it corroded under the paint. When I checked the Tohatsu warranty it did not cover corrosion under the paint. That was a couple of years ago. Warranty may have changed now but would pay to check. I have never had an issue with a Yammie.

Kankama said..
Gday

I can't see why you wouldn't go with the Yammie 9.9 four stroke. Two strokes are no good on a "heavy" cat. The Yammie has a lovely big prop and a great reduction ratio (about 3-1) that means you can stop, get going, push against headwinds etc.

I have had a Yammie 25 four stroke for about ten years and it has been great - only one issue when I put the dregs of a jerry can into the fuel tank - cleaned out the carby and back to good as new again.

Friends with Yammies almost all seem to love them. The one guy I know with a Tohatsu has had the sump rust out after 4 years. So as much as I would like the cheaper price, it may be an issue.

Go the four stroke, go the Yammie

cheers

Phil

Yes, but then he has to change the fuel lines and the tank as well as the engine, just going up to a 15hp engine will take care of the lack of power, BTW FelixdeCat I know all cats are the same in the dark, but what type of cat is she?

Bruski068 said..

Kankama said..
Gday

I can't see why you wouldn't go with the Yammie 9.9 four stroke. Two strokes are no good on a "heavy" cat. The Yammie has a lovely big prop and a great reduction ratio (about 3-1) that means you can stop, get going, push against headwinds etc.

I have had a Yammie 25 four stroke for about ten years and it has been great - only one issue when I put the dregs of a jerry can into the fuel tank - cleaned out the carby and back to good as new again.

Friends with Yammies almost all seem to love them. The one guy I know with a Tohatsu has had the sump rust out after 4 years. So as much as I would like the cheaper price, it may be an issue.

Go the four stroke, go the Yammie

cheers

Phil

Yes, but then he has to change the fuel lines and the tank as well as the engine, just going up to a 15hp engine will take care of the lack of power, BTW FelixdeCat I know all cats are the same in the dark, but what type of cat is she?

She is a Beach Marine - Macro 25.

I got a quote from the local tohatsu dealer for $3k for a new 9.8 4 stroke. Its lighter than my current 2 stroke by 5kg and much quieter. The quote includes the electric start, high thrust prop, new cables for throttle gear shift etc and the option to charge the battery. For another grand I can include the power tilt option but im not sure about that one.

I dont need tonnes of power but the hi-thrust prop sounds good for maneuvering. I have lots of vessels moored between myself and the main pittwater channel.

I will get a quote on a Yamaha next.

Fuel line has to be changed regardless, but the fuel tank is pretty new.

The battery is cactus.

I have an 8hp Tohatsu 4 stroke on my Top Hat. It lives on the stern bracket and never gets flushed, but sitting upright when not in use means most of the water drains. I bought the boat in 2009 and the engine is a 2003 model. It gets an oil and filter change with a set of plugs every 18 months or so. Very little difference in the 8hp to 9.8 in weight and the additional HP is probably negligible. Each time I talk to Cohoe Marine, they're really good and helpful, but I only ever buy a fuel filter from them......
If you can get to the motor to use the pull starter, the 4 strokes are really easy to start, so you could for go the electric start if it was a budget thing.

For the Yamaha 9.9 with all the exact same features as the Tohatsu I was just quoted by the local dealer at $4k.

So what am I buying for the 33% price premium? Not exactly sure.

At this point they are indistinguishable for me. I cant help but think that if taken care of I will probably still get what I need from the Tohatsu.

It will have a permanent connection to the fresh water tanks for flushing and a replaceable anode so I dunno.

I am really thinking about $3.8k for the tohatsu with Power Tilt. Sounds pretty gangster to me.

hi felix I have first hand experience with a single central mounted outboard on a seawind 9.6 meter 3.8 tonne catamaran .when we bought the boat in 2010 it had a 30 hp honda 4 stroke on it and had major corrosion issues but still ran ok but because it had a high speed gear ratio and small diameter prop it was useless in reverse, and very hard to stop the boat when coming into a dock, it was a 28 inch leg and I also bought a 4 blade high thrust prop for it, but it made very little difference to its stopping power ,so we sold it and bought a 9.9 high thrust extra long shaft yamaha 4stroke and never looked back ,It only weighed 45kg has electric start has a 3 to 1 gearbox ratio and a 12 inch diameter dual thrust prop, fuel consumption is 1.2 liters per hour and it ran so much quieter and smoother than the honda 30 ,We had the boat for six years and when we sold the boat in june last year I had to deliver it from lake macquarie to Darwin some 2500 nautical miles, the trip took 8 weeks and the engine did 400 hours and used 500 liters of fuel ,it pushed the boat at 5.3 knots and still made headway against fast tidal flows and headwinds ,so from my experience with the yammie I wouldnt consider anything else ,purchase price was $3800

Kankama said..
The one guy I know with a Tohatsu has had the sump rust out after 4 years. So as much as I would like the cheaper price, it may be an issue.

Go the four stroke, go the Yammie

cheers

Phil

Oy!!!! Not everyone you know with a Tohatsu has had corrosion issues after four years. Mine went through a mechanic last week with a good report, apart from the issue with its swimming lesson.

Much as I respect Kankama, I've been very happy with the Tohatsu 9.8 two stroke ultra long shaft. It pushes a 28' mono faster than the old 11 hp diesel used to. I would agree with those who say that the electric start and tilt are luxuries you could do without. I'd also note that Kankama has a lot more cat experience than I do.

Any of the small outboards with a Korts nozzle would suit.

Ok this is all really good info guys, thank you.

So lets forget power tilt. Theres an existing hole and cleat for pulling the motor up and securing it so no worries there. The electric start isn't really a luxury on this model, its kind of necessary due to the layout and the female crew ;-)

So I am buying one of these motors today.

And the prop size and gear ratio seems to be the main talking point. So here's what I have found in regards to the specs that interest me:

Tohatsu MFS9.8B:
Cost: $3000
Weight: 37kg
Gear Ratio: 2.08:1
Hi-thrust prop specs: 8.5in dia x 7 pitch

Yamaha FT9.9XEB:
Cost: $4000
Weight: 45kg
Gear Ratio: 2.92:1
Hi-thrust prop specs: 11.75 in diameter x 9.25 pitch

So it looks like I will be dipping a bit deeper into the pockets for this Yamaha. I have an 18ft wide vessel and I am closest to shore, with many vessels to pass by each time I go out so I really do need maximum stopping and maneuvering power. Clearly the Yamaha must be generating more torque to be able to run that prop but I dont really see torque mentioned in either of the spec sheets? I would think that would be something they would want to promote.

www.tohatsu.com.au/content/mfs98a3
www.brisbaneyamaha.com.au/ft9-9lex-yamaha-4-stroke-9-9hp-ultra-long-shaft-portable-high-thrust-outboard-for-sale/

UncleBob said..

Bruski068 said..

Kankama said..
Gday

I can't see why you wouldn't go with the Yammie 9.9 four stroke. Two strokes are no good on a "heavy" cat. The Yammie has a lovely big prop and a great reduction ratio (about 3-1) that means you can stop, get going, push against headwinds etc.

I have had a Yammie 25 four stroke for about ten years and it has been great - only one issue when I put the dregs of a jerry can into the fuel tank - cleaned out the carby and back to good as new again.

Friends with Yammies almost all seem to love them. The one guy I know with a Tohatsu has had the sump rust out after 4 years. So as much as I would like the cheaper price, it may be an issue.

Go the four stroke, go the Yammie

cheers

Phil

Yes, but then he has to change the fuel lines and the tank as well as the engine, just going up to a 15hp engine will take care of the lack of power, BTW FelixdeCat I know all cats are the same in the dark, but what type of cat is she?

Hi why would the tank and fuel lines need to be changed, the only difference would be the fitting at the engine, easy to change.
Also have you considered visiting an outboard wrecker and pricing having the power head transferred to a serviceable leg. Surely more cost effective.
Cheers Bob

You need to change the lines and tank or else you will have residual oil getting into your nice clean 4 stroke fuel clogging up valves, and other parts of your engine, I speak from experience, as I ruined a good 4 stroke engine by cutting corners, and doing as your suggesting.

good choice felix the yammie is the best engine for your boat ,another tip is go for the 7" pitch prop over the 9" as it will allow the engine to reach the ideal rpm for maximum thrust. On our boat the standard prop only let the engine rev out to 4500 but the 7" pitch prop allowed it to go to 5200 at wide open throttle ,the dealer will supply the 7" prop with the engine if you ask them

I'd go Yamaha 4 stroke 9.9 everytime. I have a friend who is selling two extra long shaft units with controls because he believes they are just getting a bit old (7yrs). I've worked on them and they are really good engines that someone will get for a song. I've seen the same thing on Gumtree a number of times recently.

If they are the derated 15, that's even better, same as what I have currently.
It would have been ideal if this engine was still available. The new version is not the same engine.

I'd be interested in details also if 1 engine remains available.

Glad you have something sorted Felix.
Post when it's up and running.