Yamaha FT9.9GEL four stroke high thrust long shaft 3 bladed outboard

I have twin outboards on my 38 ft cat - one 25 and one 9.9. The 9.9 pushes my 38ft 4000kg cat and 6 knots flat out.

hi R13,

I have the previous 2002 of that model, Ft9.9D series, but long shaft .
Your model has is a slimmer powerhead and slightly different gear ratio.
It is common to the 8HP. Older models such as mine that came with the boat are based on the 15HP block.
Either is still 9.9
They are a great engine, and like Kankama, I have a cat also.
Mine is 9.3m, and approx 2.5T. The single outboard will push it at about 7 knots flat out, no wind or tide.
Once the hulls get dirty, this drops to around 5-6.

The thrust is great, especially in reverse for stopping at a pier its great.
I have purchased a slightly finer pitch prop as a spare that I am yet to put on, just by way of experimenting to see if I can get easier top speed, albeit sacrificing some push. I have an anti cav plate to play with also, that might help in lumpy conditions.

Only other suggestion, consider getting a spare prop (ebay, around $80 or so).
They have a rubber drive donut that perishes and eventually splits., leaving the hub to spin separately from the prop blades, usually when you need the outboard most.

hope this helps.

yes, thats who I used.
They do a 4 blade, thats what you need.

Rowan from Ozprops emailed me back after I told him what I was chasing, and he suggested the "10x5" 4 blade.
It's still a high thrust, and they import them from the US. Cost was around $230 from memory.

My only concern was the outboards now over 15 years old, and has had a tough life being on a mooring boat, rarely gets a flush, I didn't want to go playing around too much with prop size as it will probably just add extra demand on the gearbox.

I'm getting good at oil changes, dropping the leg and the last impellor change after christmas was done in situ, via the dingy.
I probably wouldnt recommend it though unless you have to..
good luck

Select to expand quote

r13 said..
Great thanks Kankama, Azure and Crusty - really appreciated. It sounds like this will be a goer. Good tips about the rubber drive splined bush and spare prop. I am surprised that Yamaha don't have a 4 blade low pitch high blade area for the 9.9 size - as per here only 3 blade props albeit it is a high blade area design. Crusty are you aware of such a 4 blade prop for the 9.9? Appreciate advice of the finer pitch prop model you have as the spare. Thanks again in advance.

www.ozpropellers.com.au/outboard-propellers/yamaha/?gclid=EAIaIQobChMI-uq5jv6q6wIVTNeWCh0tTwGJEAAYASAAEgI-0vD_BwE

I got a four blade prop from them for my Tohatsu 8hp, goes well but "feels" like the gear engagement hurts a little- like "chunks in" but this is on a seawind 24 and it moves immediately.
2nd everyones thoughts on the Yamaha 9.9 4 stroke, I had one(the older model) on my 10M Beach Marine cat, loaded with water and stores she was about 3.4 T and would do 6.7 Kts with a single, would drop with a headwind and anything too hard best to sail as well. I've currently got a pair of the newer ones in my garage, ones a goer but the other needs a CDI unit, hope to fit them to something. Beautiful and quiet engines.
Jeff.

Hi All
I've got the F9.9c on my cat too, and I was wondering if anyone had something for doing minor services on the motor? I've downloaded the service manual which has some nice exploded views and all but I'm looking for something with a bit more guidance for doing minor services while on the boat as it's such a pain to take the motor off the boat and deliver to a service place.

I guess a photo essay for changing the oil, changing the impeller, that sort of stuff.

Thanks in advance.

Gday Jethrow

Watch Dangar Stu on his Youtube channel.

As for services - mine get

- an oil change - buy a dipstick oil syringe off ebay. - new oil filter - - when antifouled I have to wait for paint to dry so I pull the leg off and check the impeller, maybe replace (watch Dangar Stu again)- Change the gear oil - you may clean the syringe and put gear oil in the motor (watch Stu again)
- Clean inside with a nice cloth and some spray on oil - not WD40.

That is about it. Takes about an hour. Less time than it takes to take it off the boat, into the car and to the shop.

Cheers

Phil

mine is the same setup as Phils basically, in terms of service. Plus I add replacing the fuel filter.
I you are really bored sometime, I added a temperature guage to the outboard, and its saved my bacon at least once.
With it being in a pod, unless your dilligent its easy to not keep an eye on the telltale.
The last time my impellor cacked it, I was managed to see the ob temp rising, and I sailed back to the mooring instead of the planned motor around.
I just used a car temp sensor on ebay, the shortest I could fine, and an ebay chinese temp gauge.
I found a brass nut in the shed with the right thread, and tapped and braised it onto the thermostat housing. The tip penerates enoguh to measure the flow, without impeding it or the thermostat operation. 12 V to the gauge and bingo. I can actually watch the thermostat open at about 80*, then the temp drops to about 40ish.
Its the one good thing i've done.

In truth, adding brass to the cheap Yamaha alloy thermostat housing to measure salt water temp, isnt probably the wiseeast, but the Yam doesnt get flushed anyhow so i'm sure theres some good electrolysis action hapenning anyhow. I keep an eye on it, and a replacement housing is about $12 from memory.

i also tried the basic led temp gauges you can buy online, and glueing the sensor to the side of the block.
The gauges were sensitive to the power on the boat, and 2 died before I gave up