5 hp Outboard on 30’ sloop (8600 lbs) vs 30 hp Atomic 4 on ICW

[Sailon1]

Greetings,
When motoring is necessary, could a 5 hp ob push the boat in calm water or moving along with the current.
Any experience?
Your ideas are appreciated.

[thomm225]

Sure it could.

Just make sure you get the motor in deep enough

James Baldwin's Main auxiliary for his 8400 lb Pearson Triton 28 is a 6 hp 4 stroke Tohatsu Outboard.

I've used a 5 hp outboard for years on my 6600 lb Bristol 27.

Sometimes motoring 20 miles across the lower Bay

https://www.youtube.com/watch?v=ri0c5GnZ1I8

https://www.youtube.com/watch?v=cpZhq35etcw

[thomm225]

https://www.youtube.com/watch?v=ILQMj6_bI_U

6 hp outboard on Pearson Triton.

[Cheechako]

Yes a 5 hp will do it. But more HP for windy days or against the current is better.

[thomm225]

Try to use one with a 25 inch extra long shaft which is what I have.

On windy days against the current use your sails to assist the engine.

I'm motoring for leverage here on the wind but will soon tack and motorsail the remaining 15 miles

https://www.youtube.com/watch?v=ri0c5GnZ1I8

[thesaltytar]

Hello Sailon1. I do actually have some experience with this. Also, I think five horsepower will be plenty for what you need.

We had to deliver our sailboat (36' on deck, full keel with lead, no weight data because the scale on the travel lift didn't work) from Rockland to Savannah last year. Unfortunately the engine stopped working in Rockland. We sailed off the dock and figured the rest out underway.

We have a Honda four stroke BF2D 2 horsepower outboard and an 8' inflatable. We put the out outboard on the inflatable and lashed the dinghy to the transom, opened the throttle all the way and made 5 knots. We kept the tiller amidships and steered with the vessel's rudder. The outboard has an internal 1/2 gallon tank that lasts almost exactly one hour for our purposes, maybe 65 minutes. So as long as I jumped into the dinghy once an hour and topped off, life was good.

We tied a string onto the kill switch and led it to the cockpit. For docking purposes you just throttle down a bit, maybe make one exploratory pass, then on final approach yank the string accordingly and step off onto the dock. If for some reason that doesn't appeal you can tow yourself in with the dinghy but I only did that once in the beginning.

Couple notes.

Have your engine fully serviced first. The daily running should actually be good for it and I doubt you will have much problem.

Take an extra fuel cap. Pulling into Portland I lost ours overboard and in an emergency maneuver put a bunch of holes into a ziplock bag that I duct taped over the fill port (with the holes not directly lining up between the two layers of plastic) to stop the gas sputtering all over the engine. I used super glue to attach some string to the replacement cap and tied it onto the engine. Yes the original cap had the plastic T thing that supposedly holds it to the outboard, no I don't trust that anymore.

The rubbing on your transom will leave a mark. To do it over I would hang a chafe mat over the stern of the boat.

Tie your inflatable off to your boat with two lines in case the first one chafes through and definitely have that kill switch string tied off... You don't want to watch your main engine take off at five knots without you.

[grantmc]

For several years I used a Tohatsu 5hp with an 'extra long shaft' to power a 26 foot keeler. It is a 2-stroke with an in-built fuel tank. It was very successful pushing the boat at just a tad under 5 knots in calm conditions. But it was able to cope with some wind and/or current, just a little slower.

Reversing wasn't great but it was fine to back in to a slip.

[Jammer]

Originally Posted by Sailon1

Greetings,
When motoring is necessary, could a 5 hp ob push the boat in calm water or moving along with the current.
Any experience?
Your ideas are appreciated.

We had an 8 HP high-thrust Yamaha extra long shaft on our 24' Morgan and later our 26' Hunter. It provided plenty of power for those boats. 5 hp on a larger boat would work OK but would not be ideal.



Outboards do have some drawbacks for this sort of thing. One fact to consider is that they don't have large alternators so they aren't a good source of electrical power. Ours had electric start and an alternator but it only produced around 6 amps.


Outboards can get swamped and fail in a following sea, because they are so close to the water.


It is awkward to operate the controls on many installations, because you have to reach over the transom. In most cases it is difficult for one person to simultaneously steer the boat with the rudder, and manipulate the steering, throttle, and shift on the motor, which makes docking difficult.

[Sailon1]

Thank you for those excellent details. Very practical information. Using the outboard should save significant cost compared to the A4. Less pollution as well.

[Sailon1]

Originally Posted by thesaltytar

Hello Sailon1. I do actually have some experience with this. Also, I think five horsepower will be plenty for what you need.

We had to deliver our sailboat (36' on deck, full keel with lead, no weight data because the scale on the travel lift didn't work) from Rockland to Savannah last year. Unfortunately the engine stopped working in Rockland. We sailed off the dock and figured the rest out underway.

We have a Honda four stroke BF2D 2 horsepower outboard and an 8' inflatable. We put the out outboard on the inflatable and lashed the dinghy to the transom, opened the throttle all the way and made 5 knots. We kept the tiller amidships and steered with the vessel's rudder. The outboard has an internal 1/2 gallon tank that lasts almost exactly one hour for our purposes, maybe 65 minutes. So as long as I jumped into the dinghy once an hour and topped off, life was good.

We tied a string onto the kill switch and led it to the cockpit. For docking purposes you just throttle down a bit, maybe make one exploratory pass, then on final approach yank the string accordingly and step off onto the dock. If for some reason that doesn't appeal you can tow yourself in with the dinghy but I only did that once in the beginning.

Couple notes.

Have your engine fully serviced first. The daily running should actually be good for it and I doubt you will have much problem.

Take an extra fuel cap. Pulling into Portland I lost ours overboard and in an emergency maneuver put a bunch of holes into a ziplock bag that I duct taped over the fill port (with the holes not directly lining up between the two layers of plastic) to stop the gas sputtering all over the engine. I used super glue to attach some string to the replacement cap and tied it onto the engine. Yes the original cap had the plastic T thing that supposedly holds it to the outboard, no I don't trust that anymore.

The rubbing on your transom will leave a mark. To do it over I would hang a chafe mat over the stern of the boat.

Tie your inflatable off to your boat with two lines in case the first one chafes through and definitely have that kill switch string tied off... You don't want to watch your main engine take off at five knots without you.

Very useful information thank you.

[Adelie]

Originally Posted by Sailon1

Thank you for those excellent details. Very practical information. Using the outboard should save significant cost compared to the A4. Less pollution as well.

If you are talking repair/replacement costs A-4 vs 5hp Tohatsu, yes the outboard will be cheaper.

For running costs the A-4 will be cheaper for several reasons:
A. Small outboards, even 4-stroke, tend to produce less power per gallon of gas than larger gas/petrol engines.
B. The A-4 swings a much larger prop at a lower speed than a 5hp outboard, even a high thrust model, and so provides the same thrust using less power (and fuel consumption) than an outboard.

I don’t think the outboard will produce less water pollution than an A-4, all of the hydrocarbons and the blow by from the outboard will go out the hub of the prop to bubble the the water.

Whether the A-4 exhaust winds up in the water depends on the particulars of your specific engine installation. Regardless, the A-4 using fuel more efficiently means less total pollution unless it’s losing compression and on its last legs anyway.

That said I would be inclined to install an outboard in a motor well for backup and replace the A-4 with electric propulsion and batteries.

[Jammer]

The Pearsons in the high 20/low 30ish size range were highly regarded in their day (1970s). Most were equipped with an Atomic 4 with a few getting a Farymann diesel that was IMO probably not an improvement. What often gets lost in these discussions is that the Atomic 4 was a good match for these boats and was, in its day, highly regarded for reliability, ease of maintenance, quiet operation, and (compared to diesel exhaust) minimal odor.


Pearsons have the high, narrow transom stern typical of the IOR era. Sharing the stern between a swim ladder and an outboard bracket will involve some compromises. There isn't a well for the outboard and probably no practicable way to add one.


These older boats don't have much resale so it really comes down to how long you're going to keep the boat, how much money you're willing to put into it, and whether your goals involve a lot of motoring. For most people the whole point of a 1970s boat is that they're cheap. Nothing wrong with that. If the Atomic 4 is in semi-reasonable condition it probably won't cost any more to get it working reliably than it would to buy a (used) outboard and a bracket, especially if you get the correct outboard for the situation (more than 5hp).


But yes, you can get by with a small outboard, keeping in mind its limitations.



I would be surprised if there would turn out to be a meaningful difference in fuel economy.

[Jim Cate]

We had an 8 HP high-thrust Yamaha extra long shaft on our 24' Morgan and later our 26' Hunter. It provided plenty of power for those boats. 5 hp on a larger boat would work OK but would not be ideal.

Extrapolating from a HI THRUST 8 hp on a much lighter boat to a 5 hp standard on a heavier boat leads to a false conclusion of acceptable performance IMO.

To develop even its rated 5 hp, which will be required most of the time, the smaller motor will need to run at high rpms. It's tiny prop will be operating with a lot of slip and that is inefficient at best. This will inhibit operation when the conditions require more thrust, ie to windward or in chop. I don't think I would be happy with such performance... I can't speak for you!

Even though I am not an Anemic-4 fan, I think it a far better option for you.

Jim

[Jammer]

I'm in complete agreement with Jim, actually.

The OP asked whether the 5 hp would be sufficient "in calm water or moving along with the current." So I answered the question.

I agree that to windward or in chop it would not provide satisfactory power.


It would be worthwhile, if proceeding with the 5hp, to fit the shallowest pitch prop that is available for it.

[thomm225]

If the OP is like many cruisers and cannot deal with sailing without a powerful engine then he should definitely not get an outboard.

But if he would like to be somewhat challenged at times an outboard is perfectly fine for a boat of his displacement.

Most of us that have them use our sails to assist the engine as we are more about sailing than motoring, but if you are on a schedule sometimes you have to use you engine/outboard.

Some tend to forget folks sail round the world, across large bays, and across oceans with an outboard as the main auxiliary engine.

It's all about how much effort you want to expend.

It's all about what type sailor you are.

Are you the guy that uses mostly engine and maybe unfurls the jib from time to time or do you raise the main and sail the boat?

I see many cruisers that never raise their mainsail. They instead unfurl the jib and/or use their engine.

Outboards are also great for coming in your creek and docking. Not many sailboats can move 90 degrees off center like you can with an outboard. My outboard turns through about 200 degrees

Also my outboard has no alternator or electric start. I didn't want all the extra crap. No extended controls either. I didn't want those cluttering up my cockpit.

I use solar for power. I would definitely not want to run an engine or generator for power with all that racket and smell and waste fuel..

https://www.youtube.com/watch?v=uNl2tPRC-Tw