Largest boat for outboard

davidpm · #1 (**permalink**) 10-05-2010

It seems that there is an upper limit as to the size of a boat that can be reasonably driven with an outboard.

I've had the opportunity to sail a few different boats this summer.
Catalina 27 with inboard - 6,700 lb displacement
Catalina 25 with outboard - 4,550 lb displacement
Pearson 26 with outboard - 5,400 lb displacement

I'm thinking of Long Island Sound use where it can get choppy and windy.

I see a lot of C27's with outboards but they are a little too heavy as the P26 seemed to be close to the limit of what seemed to be the biggest boat the outboard could handle.

So I'm thinking that something close to 5,000 lb displacement would be the upper limit for an outboard.

What do you think?

JimsCAL · #2 (**permalink**) 10-06-2010

Had a Pearson 26 and cruised on it for weeks at a time. Main issue with the outboard was in rough weather, the prop would be out of the water almost as much as it was in due to pitching. Fine in smooth water.

Don't think its really a displacement limit. As boats get above 26-27 feet, they are more serious cruisers and an inboard makes sense.

sailingdog · #3 (**permalink**) 10-06-2010

The limitation of the size of a boat that can be outboard powered isn't the displacement of the boat, but the limitations of the prop size and gearing on an outboard. Most outboards can't take a very big prop and provide it with the lower gearing that it needs to move a displacement sailboat, and that's what you need when you get to the heavier, larger sailboats.

A 50 hp engine is all many of the 40' sailboats have, but you'd be hard pressed to find a prop that works, given the gearing most outboards have. Smaller outboards often have a "high-thrust" propellor available to them. Some outboards, which are sailboat market specific will offer a larger prop diameter or lower gearing.

Jim makes a good point as well... the larger boats will often have larger house battery banks and need the greater charging options that an inboard engine allows. An inboard engine is far more versatile than an outboard, and offers things like engine-driven watermakers and refrigeration, high-output alternators, hot water, cabin heating, etc., which an outboard can not.

smackdaddy · #4 (**permalink**) 10-06-2010

Another side of it, like Jim says above, is how you use the boat. We only have a 6hp OB on our C27, and, for the most part it handles everything we need it to. It is underpowered, so you have to think ahead and work the momentum of the boat rather than power through problems. This is fine for most of the day and weekend sailing we do.

However, we've been in winds of 30-40 knots with 2' chop and the OB struggles to keep the boat pointed into the weather and will almost come up out of the water with a big wake even though it's a long-shaft and mounted low on the transom. Sometimes it just can't keep the boat pointed into the gusts and will fall off - which is not good.

So, no way would I take it out in open water. But it's fine for the lake. And I'm sure there are dudes that have OBs on their ocean-going yachts that do just fine.

PCP · #5 (**permalink**) 10-06-2010

Quote:

Originally Posted by JimsCAL

Had a Pearson 26 and cruised on it for weeks at a time. Main issue with the outboard was in rough weather, the prop would be out of the water almost as much as it was in due to pitching. Fine in smooth water.

Don't think its really a displacement limit. As boats get above 26-27 feet, they are more serious cruisers and an inboard makes sense.

Some cruising boats have a dedicated well (for the outboard engine) on a more central position. That will solve the bad weather problems (and the propeller in and out of the water). As an example,take a look at the Presto 30 on the "Interesting sailboats" thread.

Regards

Paulo

killarney_sailor · #6 (**permalink**) 10-06-2010

Considered, very briefly, a Niagara 35 (15,000 lbs) that was for sale in Guatemala with a Honda 15 on the back. The diesel had quit and the owner had removed the engine but left the sail drive leg in place and added the Honda. The boat was otherwise very well-equipped and the asking price was about half of that of the Niagara I bought - and the broker indicated the owner was open to almost any offer. I was checking to see if I could use points to get a flight there until sanity won out over me. Always wondered what happened to that boat.

I imagine that an outboard on a boat this size would get you in and out of harbour pretty well in reasonable conditions and that would be about it. Guess the question that was asked here should be linked to some understanding of what the owner wants to be able to do with the boat under power.

blt2ski · #7 (**permalink**) 10-06-2010

I've seen a barge or two here on Lake washington with out boards. There were are a few outboards with low gearing and large props, the Seagull comes to mind out of the UK. I have not seen one in years.

The real issue as mentioned, prop lifting out of the water in bigger seas when hug off the back.

BUT< that can be solved as Paulo points out with an outboard well, such as the Presto 30 have, T-birds, I saw an older Oday with similar lines to an Alerion with a well recently.......

Marty

zz4gta · #8 (**permalink**) 10-06-2010

I know a guy who uses an outboard to motor his Soverel 39 in and out of the harbour for racing. It does pretty well, but the boat has been gutted, and the OB is either idling, or at wide open throttle. There is no in between.

PCP · #9 (**permalink**) 10-06-2010

The boat is beautiful... and the outboard looks like a bad joke. Quite an insult for such a boat

Matvolver · #10 (**permalink**) 10-06-2010

so what's the point of having a motor on a sailboat? if the winds up (hence why the prop would be out of the water) wouldn't you be using the sails? Isn't the motor supposed to be used when there isn't wind? And I warn everyone here, I'm not a sailor (yet), so positive input to my questions would be greatly appreciated