Dual vs Single Outboard

[Lyle]

As you all know I have taken on a super project as I would call it, and a few questions on power have crossed my mind. As the thread would imply, Dual vs Single outboard setups come to mind and size of outboard for my boat?

Would anyone care to take a stab at a good setup for my boat?

I ask because I saw a two dual Johnson 35 horse on craigslist and thought that would be cool. How beefy would the transom need to be.

Thanks
Lyle

[61_express]

Back in the day twin 35's were actually pretty common on boats in the 18-21' range. Mostly due to the fact that higher hp motors weren't available and the reliability factor that comes with twins. I would venture that the transom would be just fine unless it is rotten. My Uni came with twin 35's Johnsons in '61 and was swapped for a single 75 super seahorse in '64, I ran twin 55 Bearcats and now just run a single 55. There really isn't anything cooler looking than a pair of motors hangin off the back.

[Bflaherty]

When I worked at Aluminum Chambered Boats ('07-'08) we built a lot of boats with smaller twins rather than large singles. There were four big pros for running duals:

1. Smaller motor usually has lower GPH demand.

2. Redundancy for charter vessels carrying passengers out to fishing grounds.

3. Maneuverability in tight harbors.

4. Smaller motors cost less for both initial purchase as well as future replacement.

I think twins are always the smarter way to go and like Nick stated above, most 50's and 60's boats were actually designed to handle the weight because that was all that was available back then.

[Helmar]

Pretty much any of the boats I have been into, twins are NO problem. Skagits, Bell Boys, Dorsetts, not a problem with twins.

Like Brian said, you can find the smaller engine on sale and just run the pairs.
I Have heard that they Should turn opposite of each other.
Tim Jones and Tim Mattson ( last time Tim M was on was back on June 5) should be able to answer why.
Twins turning the same direction as supposed to torque you over to one side and make it harder to hang on to the steering. With the newer steering, I don't think that is going to be a issue any longer.
The harmonic's sound pretty darn cool.

Of course, this is just my opinion and I could be wrong (Dennis Miller)

[61_express]

Mine were both standard rotation and I didn't really notice much on the torque effect through the wheel but she did tend to crab a bit more at idle. But it maneuvered great. Once you get over say 150 hp i bet it would make it a bear to hold on to the wheel if you didn't run a no feedback setup. I just have the standard teleflex setup, so much nicer than the cable steering.

[DMCI]

Traditional engineering philosophy is fundamentally "K. I. S. S." As many of you know that stands for "keep it simple Stupid!"

Twins have mostly been applied for one reason. That was when the technology was incapable of generating required boat performance with only one engine. The classic example is a Skagit 20 with twin 35 outboard. Our Skagit 24 express had twin 100 Johnson's for that reason. The other reason for twins was for get home redundancy. More typically however the classic hundred horse application on express cruiser would be assisted by a 20 horse or so second outboard that could also be used for trolling. Fundamentally, the reduction in the number of moving parts made for a much more economical installation.

Do I like twin outboard boats? Absolutely. The sexiest boat I can think of right now is a 26 Moppy with twin Mercury 300+ outboards. Rip out the existing inboards and all associated systems, replaces space with fuel tanks and a star outboard bracket for big outboards. A really cool way to spend 50 grand for a lot of fun.