Catamaran with sterndrive engine (?)

[APP]

Hi,

I am considering to build an aluminum power catamaran of 18 m in a small yard. I need by all means the space in the hulls so, being not a naval architect, I thought to put 2 sterndrive diesel engines (2x300 HP) in the 2 hulls sterns, despite a less easy maintenance, by designing the hull stern properly to receive the sterndrive.
Some marine engineers tell me they have never heard of something like this in a catamaran, but only using outboard engines.

May I ask you here why the sterndrive is not a realistic solution and why?

Thanks
Regards
APP

[Alik]

Plenty of cats have sterndrives, some of them designed by us...

[thedutchtouch]

Originally Posted by APP

Hi,

I am considering to build an aluminum power catamaran of 18 m in a small yard. I need by all means the space in the hulls so, being not a naval architect, I thought to put 2 sterndrive diesel engines (2x300 HP) in the 2 hulls sterns, despite a less easy maintenance, by designing the hull stern properly to receive the sterndrive.
Some marine engineers tell me they have never heard of something like this in a catamaran, but only using outboard engines.
May I ask you here why the sterndrive is not a realistic solution and why?

Thanks
Regards
APP

do those marine engineers design catamarans with outboards only? and did they want you to pay them for one of these designs? that's probably why they told you they'd never heard of anything else working.

[APP]

Hi,

Thank you for your replies. Very good information for the use of sterndrives. The old question may arise here again: Yanmar, Volvo or other?

It is noted in some pictures that the transom must have a flat surface of max 0.5x0.7 meters for the sterndrive installation and an inclination of 13 deg. (if this is a standard for all engines).

To sum up, apparently the sterndrive solution may present the advantages of more space in the hull for accommodation, we do not need to face some problems related to steering, shafts, gearbox, maybe the V-drive if it was a solution, the shaft inclination, complicated propeller selection, etc. and perhaps the sterndrive may be a more economic solution after all. The disadvantages may be a more difficult maintenance, difficult stern docking, attention for people swimming around the stern, no controllable pitch propeller … what else?

Best Regards
APP

[Alik]

I believe experienced designer can solve all these problems with success. Actually there are no problems of using sterndrives on cats, but one needs to consider craft application and particulars to give clear answers. Those who know how to treat catamarans design are not likely to share too much of general experience on forum.