tophatyachts.com

I'm investigating putting a Yamaha 4 stroke FT9.9 GEPL into a MK3 has anyone achieved this.
What did you do to make it happen.
And any suggestion's that may help.
dutyfirst00

I measured one up and it wouldn't fit in the well

My Tohatsu 8 4 stroke didn't fit in the well either. It's hanging on a lifting bracket of the transom, which had to be re-inforced on the inside. Works quite well, and whilst it's pretty fast, you may get some cavitation if you're up the front and in a steep chop.

What outboards are being used prefer 4 stroke
dutyfirst00

For my money, I would rather have a smaller motor in the well than a bigger one hanging on the transom. Far less chance of cavitation in rough seas when you need it, and easier access to the motor if you have a problem.

Example on my current boat with transom mounted motor- hit the "washing machine" area near Barrenjoey headland in Pittwater, prop out of water, revs up then hits the water when it drops back, prop shear pin gone. No way to get the motor up into the cockpit to replace shear pin. Simple job if the motor is in a well.

I agree with Ianb that a motor mounted in the well is to be preferred. You need to get the prop as low as possible and as far forward as possible to avoid cavitation in a choppy sea.
Having the motor in the well allows you to mount it lower than if on the transom as it is protected from waves.
As Ianb says, it also makes repairs at sea much easier. I once caught a line around the prop and was able to lift the motor out and remove the line quite easily.
The downside of having the motor in the well is that you have to lift it out at the end of each day. To make this easier, a lightweight motor is preferable. 2 stroke engines are significantly lighter than 4 strokes.
I recently replaced my Mariner 8HP longshaft, which had served me well for 25 years, with a Tohatsu 2 stroke 9.8HP ultra-longshaft. This gets the prop deep into the water as shown in the photo below. The Tohatsu weighs only 26 kg so is significantly easier to lift than the old Mariner which was several kg heavier.
In contrast the FT9.9 is 49 kg. This weight mounted off the transom will adversely affect the trim when sailing.
Another motor worth considering is the Yamaha 2 stroke 8HP longshaft. This has a slightly shorter shaft than the Tohatsu and is more expensive but is generally regarded as being better quality and comes with a dynamo (very useful if you intend to have an electronic autopilot) and special prop which gives good reverse thrust (useful when coming into a marina).

Steve

Steve- What make self steering wind vane gear do you have?

Ian,
The windvane is homemade, mainly copied from commercial models.
Steve

Thanks for all the help I have decided to stay with a 8hp 2 stroke Yamaha. I have measured the engine compartment and worked out what mods to do at a later date. again thanks.
dutyfirst00

I've done lots of investigating on outboards as ill be needing one soon.
The F 9.9 4 stroke comes in a long shaft and a ultra long shaft. I was really keen on these outboards until i discovered that the long shaft (20 inch) has a electric and Manuel, where as the Ultra long shaft (25 inch) is only electric. I think this is a bit of a down fall, because 5 inches is a fair bit.
I think I'm sold on the 9.8 Tohatsu 4 stroke 25 inch long shaft because its Manuel, finding the ultra long shafts is hard as there all electric.
I know for a fact that it wont fit in the well has i was using a new 2 stroke 9.9 short shaft Yamaha which was way to big!
Don't forget its more about the prop. I'm sold on the 4 blade, with little pitch cant remember the exact dimensions off the top of my head.
But my advice is modify the well its not all that hard.
Good luck in the outboard shopping,

Dawn Breaker
P.S I'm rubbing back the top sides because the primer showed up many imperfections that i wasn't happy with. While rubbing away at the transom i found some history.
Turns out she spent some time at Hobson's Bay Y.S in Port Philip Bay and Carine's. No stranger to the ocean or road hah