close or further apart?

eksrae · 09 April 2003, 04:19

When mounting twin outboards what performance differances do you get mounting your motors close together or far apart?

Jelly · 09 April 2003, 08:21

Greetings Eksrae
My impression was that it was a trade off, wider appart for better manoverablitiy when working twins vs power, hydro dynamics and fuel ecconomy.
Come on guys and gals, is this correct?
Jelly

Jonny Fuller · 09 April 2003, 09:00

Having the motors as close together as pos is a racing thing! It makes for better average speed, as the closer they are together, the lower they can be on the transom (they're further down the deadrise)with the same anti-ventilation plate height, the thrust line is closer to the centreline of the boat in the event only one motor 'biting' ,and generaly better handling at high speed!

But crap in the marina!

gavin · 10 April 2003, 18:48

Think about maintaince be able to work between them if it arises,do you have oil entries on the right of the motor for trim tilt etc,this sounds fairly obvious but ensure the motors dont hit the tubes when turning, but have you thought about camber I am told this improves stability when turning (catamaran) here is a pic to try to show you gavin

Phill · 10 April 2003, 19:22

? Is your example not more for getting "clean" water to the props behind the keels versus width of transom left inbetween tubes than anything else ?

gavin · 10 April 2003, 19:54

This set up was present in the boat when it came to us, it apparantly improves stability when turning ,as we are a Catamaran,I have only seen it on Cats gavin

jwalker · 10 April 2003, 22:03

Keep them as close together as possible, I reckon.

Toe them in a wee bit to preload the steering.

JW.

Phill · 11 April 2003, 07:15

On a trihedral hull, centre deep V, I got the best all round results with far apart, and toed in. Not counter-rotating however, and I required manoeuverability (or how ever you spell it !) and sea keeping ability more than speed.

Jelly · 11 April 2003, 07:55

I know its not a RIB but on a dory 17 we found the furtherest appart made for the best manoverablity, didn't care about top speed - though she was no sluch either!
Jelly

eksrae · 11 April 2003, 14:43

there must be a happy medium somewhere? good handling as well as speed. I guess the only way to find out is to move them around?????