Inboard to Outboard?

[Talbot]

I had an outboard powered cat for a number of years.
Advantsges
Cheaper to purchase.
Any problems and it can easily be dismounted and worked on in relative comfort

Disadvantsges
High fuel cosumption
Cavitating props
Loss of drive in bad weather
Need for storage of petrol
Need to transfer petrol always at the wrong moment
More difficult to throttle and change gear so manoeuvring can be a. Pain
Low alternator output.

[crossbow]

30’ and under, O/B all the way, especially if you have a stinking old Buhk, Westerbeke, etc Etc. Ask your wife (wives). A brand new Yanmar or Beta, yes lovely.
But a 6 hp Tohatsu or 9.9 Yamaha will, in my experience save you a lot of grief (and money).
I don’t particularly like the brackets and agree with most comments about them. Best to build a well, preferably one that you can CLOSE. There’s a wonderful YouTube on it somewhere. The Yammy is an incredible motor. I had one on my Frans Maas 33 (all teak construction). Pushed along at hull speed no problem.

[wyb2]

Originally Posted by crossbow

…There’s a wonderful YouTube on it somewhere….

This one?

https://youtu.be/2ibTleP5clg

Guy does a great job, though I think it took a bit longer than the 1 afternoon that it feels like in the video.

[Jdege]

I have a Vaitses/Herreshoff Meadowlark. L. Francis Herreshoff did the original design as a narrow 33' shoal-draft ketch with leeboards, instead of a centerboard to keep the cabin interior clean.

The original design had a pair of 5hp gas engines driving a pair of props.

Alan Vaitses did a 37' version in fiberglass, back in the 70s. Still laid out for dual props.

Mine only has one prop, powered by a 27hp diesel, with a pair of 25 gallon tanks.



With just the one prop, laid alongside the keel the way it is, it's impossible to steer at low speeds. There's no prop walk to speak of.

The diesel hasn't been maintained well, and it's way overpowered for what the boat needs, and I've been thinking about pulling it and putting in a pair of electrics.

Originally I was thinking of mounting pod drives where the existing prop is and the missing prop should be.

But recently I began considering electric outboards. There are advantages and disadvantages, but for me a major advantage is that I could install them and get them working without removing the diesel. I'd pull the diesel eventually, but I could do that at some later time. I'd not be looking at extended downtime.

And future maintenance would be simplified.

[valhalla360]

Originally Posted by MicHughV

Besides the many performance issues listed above, outboards are gas guzzlers..be aware of that....run time on a 5-6 gallon tank will be measured in a few hours.
Filling up the tank again, from another container on a moving boat will be tricky.
Remember, you'll be dealing with gasoline, not diesel.

It's really a two person job...one person on the wheel/tiller....the other on the engine throttle/gearshift controls....can be done by one person off course, but tricky...

Outboards are best used on relatively calm waters.....with little wave action to lift the prop out of the water....even with an extended shaft.....

Have realistic expectations on what propulsion power a small outboard can provide.

Lastly, outboards have dismal performance in reverse. Learn to understand exactly what to expect from your outboard in reverse when time comes to dock, etc.

We had a 25hp and a 5-6gal tank is good for 5-6hr at 6kt cruise speed on our 34ft catamran but we had it plumbed into a pair of 18gal tanks and a 6 gal outboard tank with a 3way valve. We could go a couple days non-stop if we needed to.

I'd rather spill a few drips of gasoline than diesel in the cockpit. Diesel will leave a smell forever. Keep in mind with the engine outside of the hull, most of the fume issues go away (our tanks were bottom vented over the water, so that wasn't an issue either).

Our outboard was controlled and steered from the helm...no issues needing two people.

As stated before, strapping an outboard onto a boat never designed for one will likely get marginal results. Putting it on a boat designed for an outboard will be a totally different experience.

One other thing...since the outboard provides directional thrust, I can do things a single fixed inboard can't.

[valhalla360]

Originally Posted by Jdege

One apparent advantage of outboards is that you can lift them out of the water when sailing.

The brackets can be raised by a foot or so, and the motor itself can be tilted.

But how feasible is that, when an outboard is hanging off the transom of a sailboat, instead of just a dinghy? How hard a reach, leaning over the stern to pull up the motor?

Ours was mounted on a sled that could raise it out of the water.

While it helped with sailing, the bigger benefit was no corrosion as the motor was completely clear of the water. After 5yrs, the zinc was in like new condition.

[valhalla360]

Originally Posted by Talbot

I had an outboard powered cat for a number of years.
Advantsges
Cheaper to purchase.
Any problems and it can easily be dismounted and worked on in relative comfort

Disadvantsges
High fuel cosumption
Cavitating props
Loss of drive in bad weather
Need for storage of petrol
Need to transfer petrol always at the wrong moment
More difficult to throttle and change gear so manoeuvring can be a. Pain
Low alternator output.

4 strokes (particularly EFI) negate a lot of the fuel consumption issue.

Storing petrol, isn't a big deal on a cat with properly installed tanks (bottom vented above the bridge deck.

A little planning negates fuel transfer issues. Only once did we have a tank run out while motoring. I quickly flipped the valve to a different tank and the engine never fully died.

No more difficult to shift assuming you have helm controls.

[Happ]

Originally Posted by thomm225

I'd say 27' or so max for an outboard on a bracket. Although James Baldwin of Atomvoyages website has put 6 hp outboards on 28'- 30' sailboats in the well though (Alberg 30, Triton 28)

I have used mine, a Mercury 5hp 4 stroke w/25" extra long shaft) in some pretty rough conditions over the last 11 years

Get the bracket low and get the extra long 25" shaft. My outboard will stay in the water in some pretty lump seas. see video

The outboard replaced a 10 HP Bukh diesel. The 5 hp outboard pushes the boat at minimum a well as the 10 HP diesel did. Up to 5 knots in calm water

Good news is if it's rough it's usually windy so you can sail. In the video I am just getting some leverage for the last 15 mile sail home and getting around some anchored tankers

I have also motored the 20 miles across the lower bay with my 5 hp outboard

Photo of Robin Lee Graham shows the outboard he used as his many auxiliary engine to sail 3/4 the way around the world. That boat was 24' though

In cloudline video the wind had been completely calm until this cloudline came by. I had been motoring so just left the outboard down and running as it passed over but unfurled the jib

James has started putting 10hp motors in some of his boats. Much better performance and quieter. He uses a 25” shaft and hangs it underneath the overhang. It’s brilliant.

I’m a sailor so I only use a motor when there is no wind or coming into unsalable area.

[Hasbeen]

I used to run a Great Barrier Reef tourist boat day trip operation, with a capacity of 750 passengers. To support this operation I had 5 glass bottom 25 passenger boats, 8 dinghies of 12 or 14Ft, 3 of 20 passenger punts plus a couple of water taxi type 12 passenger cats with twin 115HP & 150HP outboards respectively. All up there were 20 outboards with the majority 25HP.


As a commercial operator I received only 6 months warranty, but still found the only economical way to run outboards was to keep them in warranty, thus I traded every motor at 5 months & 30 days. As a large customer I could demand the dealer keep one of each size motor immediately available as a loan motor WHEN one of mine broke down. It is reasonable to say I hate outboards.


To be fair, mine were being run by young launch masters, not owners, which I'm sure had some effect on the reliability of mine.




On the other hand I had a period of a couple of months while fitting a new different diesel to my 40Ft yacht, & was using a 9Ft rubber dinghy with a 4HP outboard to get my yacht home to a very quiet sheltered marina after Saturday races. The sea breeze would often die, leaving me with tying the dinghy along side to drive the becalmed yacht a couple of miles, which it did quite happily.


Regardless I would not ever depend on a stern mounted outboard to cross any bar in other than totally flat conditions.

[thomm225]

Originally Posted by Happ

James has started putting 10hp motors in some of his boats. Much better performance and quieter. He uses a 25” shaft and hangs it underneath the overhang. It’s brilliant.

I’m a sailor so I only use a motor when there is no wind or coming into unsalable area.

Most of us with small outboards on our boats have to be sailors also.

My first 5 sailboats didn't have engines.

I mainly raced beach cats for 15 years before getting this old Bristol. It was power boats before that owning my own from around 16-24 years old.

So far I have had two different brackets. Same brand except this time I replaced the hand knobs with Teflon nuts at install

Photos from 2015 and 2019.

My 5 hp 4 stroke Mercury has the 25" extra long shaft and an adjustable bracket with maybe 12" of adjustment range

[Happ]

Originally Posted by wyb2

This one?

https://youtu.be/2ibTleP5clg

Guy does a great job, though I think it took a bit longer than the 1 afternoon that it feels like in the video.

James has told me the build of an outboard motor well on an Albert with a slit cut in the hull so you can raise the outboard, making the compartment watertight with 2 shelves for gas cans, covers for the slit and a reconfigured hatch is around $5,000.

[Happ]

Originally Posted by thomm225

Most of us with small outboards on our boats have to be sailors also.

My first 5 sailboats didn't have engines.

I mainly raced beach cats for 15 years before getting this old Bristol. It was power boats before that owning my own from around 16-24 years old.

So far I have had two different brackets. Same brand except this time I replaced the hand knobs with Teflon nuts at install

Photos from 2015 and 2019.

My 5 hp 4 stroke Mercury has the 25" extra long shaft and an adjustable bracket with maybe 12" of adjustment range

I was responding to someone’s comment about using an outboard in heavier seas or crossing a bar. I was just saying because I sail I don’t use a motor very often. Usually only to get into a harbor or a very restrictive area where there is limited maneuvering space.

I meant no insult or to suggest others aren’t sailors.

[thomm225]

Originally Posted by Happ

I was responding to someone’s comment about using an outboard in heavier seas or crossing a bar. I was just saying because I sail I don’t use a motor very often. Usually only to get into a harbor or a very restrictive area where there is limited maneuvering space.

I meant no insult or to suggest others aren’t sailors.

I didn't think it was an insult.

I posted the videos of the rougher water to show some doubters that outboards don't necessarily come out of the water in anything other than smooth water

I was motorsailing around some tankers here to save time on a Sunday Morning on my return from a few days of cruising the Bay, Soon as I got around enough it was back into sailing mode or if I needed to point close leave engine down and running just a bit over idle

Could have sailed around them but the current was wrong also and it would have just added more time to my return.

Had I not had to go to work on Monday I wouldn't have wasted the gas. I only keep about 3 gallons or so onboard unless I know I'll use it up quickly on a light wind return or something.

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

[BBill]

Depends on the boat and where you are motoring. Cavitation is the main issue and the longer the boat the more it cavitates in big water. It can't be fixed with props...I tried. I have a 20' trailer sailer with 25" shaft and it does fine in anything short of running an inlet with breakers. I had a 28 ketch and 32 sharpie with outboards and it was a totally different story. I motored down the ICW and to the Bahamas in millpond conditions without a problem. But...we basically abandoned using the ob engine in any other sea conditions due to cavitation. Sometimes the powerhead would get dunked and then the prop would clear the water. I came back and bought an inboard for cruising and never looked back. An outboard definitely makes a better sailer out of you though.

Fuel burn? My 5 hp 4 stroke Tohatsu outboard burns .5 gph and and the 7 hp volvo diesel I had burned one pint an hr and the 16 hp volvo I had burned 2 pints...both at near full throttle in heavy boats. So don't rely on the outboard giving anywhere close to the same range.

[thomm225]

First point is many of us that have outboards would rather not run the engine at all so range isn't an issue.

Who wants to motor for hours on a sailboat?

Many of the old diesels smell and leak oil inside of the boat so an external outboard is great so you can have a clean boat.

After I removed the ancient Bukh Diesel from my boat, I then removed 2" of sludge from the bilge then cleaned the engine compartment repeatedly until all the oily residue was gone.

This took months.

It was so nice after getting that smelly, leaky diesel out of the boat.

Since all my other sailboats didn't have engines, I wasn't used to living around the smell of diesel and oil so once the diesel engine was removed it was much better staying over ight onboard

Removing the diesel and all it's associated equipment also lightened my boat by 400 lbs plus there was no prop dragging through the water while sailing

And no leaks from a stuffing box.