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Twin outboards

Posted: Thu Feb 28, 2013 11:36 am
by Andy Garrett
Anyone ever consider twin 25s on a Zip or maybe twin 30s on a Malahini before?

Re: Twin outboards

Posted: Thu Feb 28, 2013 11:56 am
by pamelalynne1
Twin outboards on the Zip or Malahini may not be a good idea. It might necessitate a redesign of the motor well and extensive reinforcement due to the weight of two outboards. One 50 HP does not weigh that much more than a 25 HP. Certain designs, such as catamarans, may give better performance with twins; but I do not see any advantage on the two designs you mentioned. BTW, two outboards cost twice as much to purchase and to operate.
I'm sure some of the Zip and Malahini builders will chime in here.

Re: Twin outboards

Posted: Thu Feb 28, 2013 1:54 pm
by vupilot
One thing you have to keep in mind is that the performance of two 25hp is not going to be equal to one 50hp. Its going to fall somewhere in between in compairable performance. It is cool though and you do gain redundancy but other than that their really is no practical reason to do it other than its just plain fun. Here is a nice old woody with vintage twin mercs.
http://www.youtube.com/watch?v=tmiEIM_qZdo

Re: Twin outboards

Posted: Thu Feb 28, 2013 7:51 pm
by Retroman
Unless you just had a real compulsion to do it, or came across a real good deal on 2 old Mercs (like I did) there would be no good reason to do such a thing. I think about it everyday. Now that your into retroboats and antique outboards, I'm sure it's only a matter of time before you do it. LAUNCH DAY IS FOUR WEEKS AWAY.

Re: Twin outboards

Posted: Thu Feb 28, 2013 8:33 pm
by rjw
But could twins add maneuverability, a la twin screw inboards?

I'm looking to do a Waterlodge two houseboat with an 8' beam - and jave been thinking twin outboards might help with maneuvering

Re: Twin outboards

Posted: Fri Mar 01, 2013 9:40 am
by pamelalynne1
The maneuverability advantage with twin screw will depend on how far separated the two shafts can be placed. In most inboard designs they are separated by nearly half the beam width. This does give an advantage to turning and many can turn around nearly within their own length. The possible difficulty you may have is the fact that you will have a 2400 lb hull plus the weight of all your fixtures and equipment with only a 70HP maximum rating. You could also think about using bow thrusters, a much less expensive alternative, although there are pros and cons to the advantage of using them on boats the size of the Waterlodge. I would put that specific question to the GlenL teamfor a more definitive answer.

Re: Twin outboards

Posted: Sat Mar 02, 2013 5:09 pm
by rjw
Thanks -

I'm not sure how much horsepower I need - I'm looking to move pretty slowly (Old age <G>)

Re: Twin outboards

Posted: Sat Mar 02, 2013 8:25 pm
by pamelalynne1
Two 35 hp outboards will not give you the thrust of one 70hp as was mentioned earlier. In any case, a 70hp is not going to break any speed records. I almost goofed and said "at any rate" :lol: I still think this is really a question for someone with more expertise on the subject.
And stop complaining about old age. I have two great grandchildren and I am just finishing my Stiletto ski boat build; and I might have to build something faster. One of my friends has a Sutphen jet boat called "Blew By You" that does over 70; and I have to be able to keep up with him. We started racing each other when we were teenagers.
Never underestimate the determination of an old lady. :lol: :lol: :lol: :lol: