Dual engines - how close - please help

[Toffen]

Hi!

I consider to add another Promax 300 on my Phantom 25. The width of the transomedge is 33 inches in total. The boat width is 5,5 feet.

How close can I mount the two engines - measured centerline to centerline - without causing problems.

Mercury reccommend a minimum of 26 inches centerline to centerline. This is required to eliminate cowling interference during lock to lock turns if one of the outboard would be in full tilt position, while the other outboard are in vertical running position.

However, I will run with both in vertical running position, and tilt them simultanously.

Please help!

Cheers, Toffen G - Norway

[Mark75H]

The props can't touch....

[us1]

My Silverwing has them very close together and Stokers new twin is even a little closer than that. I will mesure the Silverwing tomorow.

[Raceman]

Toffen, Sam says the props cant touch..........the stacks can't either.

[Toffen]

Hi!

Looking forward to your measurements!

Cheers, Toffen G

[us1]

The Silverwing is 24 inches apart to the center of the motors. One thing to keep in mind is the Silverwing is a full tunnel and a Mod VP bottom may not like the motors put just anywhere. They may have to go in the tunnels or right on the inside edge of the sponson.


http://raceoutboards.com/images/DCP_0015.JPG

[Toffen]

Hi!

Thanks!

I have a classsic offshore hull with a 24 degree v bottom. The beam is 5,5 feet, so its rather narrow to be a 25 feet long boat.

Since the maximum width I have to work on is 33,5 inches, the space is limited. If I mount each engine on each end of the transomedge, there will be 8,5 inches between engine transom brackets. And I am not shure if this is enough at all. This is equivalent to 20,86 inches from engine centerline to engine centerline....

Since you have 24 inches between your engines I doubt I have room for two engines direct on the transom... I can make a setback bracket with 2-2,5 inches of setback, but them I am afraid the boat gets too tail heavy... I am going over tomorrow to measure again!

The strange thing is that they have twin 2.5's on Phantom 23 which is even narrower...

Thanks and cheers, Toffen

[us1]

Talk to Al Stoker "Racer", his new twin Stoker has the motors very close together.

[hydrostreamvulture1]

US1 that silverwing is sick lookin damn wut top speeds do u reach with that thing? def should get tha boat of the year! it is made for twin engines or wuz that ur idea? very nice boat luv the pics keep them coming!!!!

[us1]

It came with single or twins

[Toffen]

Hi again!

Rowdy told me just now (Boatsetup.com) that most V hulls have twin engines 20 inches from engine centerline to engine centerline. So I trust this is fine. Any ideas?

Cheers, Toffen G:D :p

[Toffen]

Hi!

How close do you have your engines?

Cheers, Toffen G

[Gerben]

Toffen,

I was just wondering; A while ago i seem to remember you reduced the setback because you had some trouble with the boat sitting lower in the back and backwash at sea.

Wouldn't adding another motor make this far worse, even dead against the transom?

Just wondering,
Gerben

[Toffen]

Hi!

The best thing to do would be to buy two Promax 2.5 (280HP) engines due to overall weight (350lbs against 470 lbs on each engine). But i do not have the cash...

When I had 12 inches of setback this was equivalent to 500 kilo in total on the transom (210 x 2 + CMC 35 kilo + 45 kilo bracket). It proved to be faster than 5,5 inches with 2 mph. However, handling in high seas was not that good. Too tail heavy. There was no backwash, but the boat looked like a Fountain!

If I mount two Promax 300 direct on the transom, the total weight will be 410 kilo. 90 kilo less than last time, and it should be "ok"... I hope!

They run 2 x 2.5's in offhore races on the new Phantom 23 in UK and Europe without problems mounted direct. Sometimes they use powerlifts as well. However, a 2.5 weight is 165 kilos each...

Have ou seen any twin installations on Phantoms in your area?? I remember many years ago, they had twin Yamaha 225 on a Phantom 20 feet rig... scary! I have also seen the new Phantom 23 with both twin 2.5 litre and twin 3.0 litre engines. I do not know how they handle, but they should run in excess of 100 mph....

Cheers, Toffen G

[Skirace]

how about 3 motors on a 21'??

[2.5-21]

the closer the better