Inboard to Outboard?

[Don C L]

So I have forgotten which thread discussed the efficiency of an outboard, but kept more careful measurements this time with my 29', 8000#, 22.5' waterline Sparkman and Stephens hull with a Tohatsu 9.8 hp, with carb, with a "power prop" but not the power gear ratio. I was actually happily shocked to find even better results than I thought I had before. In calm water, in no or light wind but the mainsail up (granted that probably did offer some help) my average over 65 miles was 0.65 gallons per hour at 5.7 knots (hull speed is supposedly around 6.3 kts) which was about 3/4 throttle. My first leg I went 27.16 nautical miles on 3.4 gallons of high octane gas. This speed was SOG but over the entire route I think my time going against and with any currents was about equal.

And I am not necessarily endorsing outboards over diesel inboards; my boat was built with only a Seagull outboard in mind as an auxilliary!

[gulfislandfred]

50 years on the Salish Sea, with both diesels and four stroke outboards on displacement hull sailboats. Fuel consumption has never been an issue, even at today's high prices.

23L/5gal of gas gives me 8 to 12 hours of motor time at cruising speed, depending on boat length, and weight. Might be 10 to 15 hours for the same amount of diesel.


I think the 9.9 outboards, even High Thrust, are OK up to about a 32 foot boat.



Preference and opportunity will determine what's best for each person.

[Munoz]

James at Atom voyages has reacent video on a refit of a cape Dory 36 with a 9.8 tohatsu and a 6 kw epropulsion outboard. I think he was getting about 6 knots at full throttle with either motor.
I have a Yamaha 9.9 high thrust extra-longshaft mounted on the transom of a 35ft, 9 ton steel cutter, it's proven quite adiquite for me so far ( form Europe to French Polynesia) for the Panama canal to maintain the required 5knts speed I had to run it at just over 4000 rpm (about 5kw), which consumed about 6 gallons over the 30 miles. The whole prop coming out of water has not been an issue for me personally (if there is wind I sail) but if you want to treat the boat s a motor-sailor I guess you might be less satisfied and a transom mounted outboard may not be the best choice. I do like the Tohatsus, especially the 6hp sailpro (which would be my first choice for boat in the 3-6 ton range) and their propane fueled options, but once you get up to around 10 tons the Yamaha 9.9 high thrust is probably worth paying a premium for(20-30%) on account of the lower gear ratio and bigger (12inch) prop. If you're on a tight budget and looking at two strokes, Suzuki made some nice 9.9hp extra-longshaft outboards back in the day but they are getting a bit long in the tooth now I guess

[Happ]

Originally Posted by Woody5

I see a lot of older 30+ ft sailboats here in Florida with an out board mounted to a bracket. Is that a viable solution for an older boat with an ailing inboard engine?

If you go on YouTube and lookup Atom Voyager. James designed an outboard motor setup that he installs inside the overhang of the stern. The advantage is that you eliminate the expensive cost of maintenance and/or replacement of a diesel. For instance on an Alberg 30 (#9000) he removes the original Atomic 4 weighing 332# plus the gas tank, filters, hoses, alternator, fuel tank, etc I’m guessing about 400#. And drops in a 10 hp outboard that can be tilted up for drag free sailing. You don’t need a $3000 folding prop either.

It’s easy to find someone that can work on an outboard. DIY is very easy with very few parts and tools required. To me it’s a no brainer

[gulfislandfred]

My old Newport 30 had an equally old atomic 4 inboard, which I'm slowly removing.
The 9.9 25" Yamaha high thrust outboard is plenty of power to be a motor sailor when there's no wind. I have collected a few parts motors. I could put together a whole spare motor from parts if I need to.
Just to get in and out of harbour, and to move in flat water, I can see how the outboard would be fine for a bigger boat, especially a high thrust outboard.


I remember people who used British Seagull outboards on 40 foot sailboats back in the 1960s, just to get in and out of the dock. I had a Seagull Silver Century Clutch Plus on my old Seabird Yawl. I appreciate the electric start on the Yamaha I have now.

[Don C L]

Originally Posted by gulfislandfred

I had a Seagull Silver Century Clutch Plus on my old Seabird Yawl. I appreciate the electric start on the Yamaha I have now.