Surface drives on Sunseeker Superhawk

[henrik igland]

Hi.
Just bougth a Superhawk 50 without engines. This one have the tripple Trimax drives and the ZF110TS gearboxes still mounted.
Thinking of installing 2x480 Yanmars in stead of the 3x420s that used to be in it. I will loose some topspeed but it should still make 40+knots.

Will there be any advantages of mounting the drives closer to the center of the boat? This will include moving the enginemounts etc. Or will this work properly with just removing the center drive and run the boat with the two outer drives in their original position?

Here is pictures of the stern as it is today

[rasorinc]

I would leave them where they so you do not have to change the rudders.
Spread wide gives better perforance and you can steer with power if something happens.
Wonder what the fuel burn was with 3-420s Wow. Send me a note if you want to sell the center unit.

[mydauphin]

Wow, kind like someone getting a Ferrari Enzo and wanting to put a v6 to save on fuel.

[henrik igland]

Well the third engine gains approx. 5knots... The fuel savings is not the issue and a pair of new 480 Yanmars is not to be compared with a "V6" if you know what I mean...

In the day of $2000 a ton herring, MANY boats in Alaska wanted to be the first to the fish, then run on one when transiting. All that I know are happier and almost as fast with just two now. Though I don't agree with far apart engines being better, to each their own there. I think it's all better having more space and less weight. I have no idea about how it will effect the boat's balance but I am confident that you can find a balance by moving batteries, tanks, and such.

[henrik igland]

Originally Posted by rasorinc

I would leave them where they so you do not have to change the rudders.
Spread wide gives better perforance and you can steer with power if something happens.
Wonder what the fuel burn was with 3-420s Wow. Send me a note if you want to sell the center unit.

Will probably sell the center unit. Have not picked up the boat yet but will let you know

[PetterM]

I don’t think there is much to be gained by moving the engines/close together at this relatively low speed considering the hassle of rebuilding the transom. Around 40 knots sterndrives would also be a good alternative.

[hhhhar]

i think it will increase the time that boat gets on planning if you mount the drives closer to the center of the boat so it will increase the fuel consumption

[Frosty]

2x 6 bladers and a 5 blade center ---interesting.

The big Yanmars are heavy. You may need a new set of props, those 6 blade Rollas are expensive, I hope you have loads of money.

[henrik igland]

PetterM:
Since the Trimax drives are allready there I will be using them. Far more solid compared to sterndrives. Don`t think any normal sterndrives handles 400++ diesel HPs.

hhhhar:
Ok, but how will this affeckt the plane time and fuel consumtion?

Frosty
I would not say the Yanmars 6LY series are that heavy... Approx 650kg? By removing one engine and increase the power from the two others I think the props are somewere close to the rigth size. I do have a set of lower pitch 6blade props (same style) and a set with 4" higher pitch props. The high pitch propellers can work if i only run 1.st gear but as I said I think the ones on it will work fine with the 2. step gearbox. And you are rigth, they cost a fortune...

[PetterM]

Trimax drives are extremly solid.
If you were not planning to use the yanmars then a volvo D6 sterndrive package might give good performance, similar to what they have on the latest version of the superhawk.

[henrik igland]

Yes I heard the Volvo sterndrives are good but i don`t dare to install the D-engines