Inboard vs. Outboard for Cruising

[coastalexplorer]

So much for Merlin engines in spitfires and failing bridges where did all that come from?...Many thanks for the back on topic comment about outboard swamping in the San Juan Islands.

As stated previously we usually use a 2 horse power British Seagull Minus on the walker bay 8 which is perhaps immersed a bit deeper than the design specification due to crew weight...but with anchor, chain and Rode in the bow for safety and boat trim: we seem to get away with it. Also it is possible to adjust the distance between the propeller shaft and the clamping bracket on that one: though I have not bothered to do it yet.

During July we tried to transit through the Canal between the Pender Islands with the 2 hp heading west and had to bare off before passing under the bridge. We tried again and succeeded later in the day, So this is what prompted the curiosity thought to acquire the 4.5 horsepower British Seagull to try it out on the walker bay 8, I did not think the the additional 12 pounds difference between the two would be such a huge issue. (The adjustment of motor height on the Century model of 1963 vintage is not possible)

I conducted the test in the calm sheltered waters of the Deas Slough of the Fraser river. We had more push against wind and current, but no appreciable increase in speed. However the motor did not seem to be able to reach top revolutions possibly due the the immersion preventing the exhaust from escaping efficiently, thus causing an excessive back pressure. Back in the close proximity to the boat launch ramp Three power boats nearby heading in different directions churned up the water causing a partial swamping of the dinghy and the outboard motor died. Causing it to subsequently refuse to start. One of the ski boats seeing us using the oars towed us to the dock. The next day back at the workshop it started on test without any difficulty.

Thus I find the report of the problem in the San Juans islands interesting and possibly similar to my testing the 4.5 HP experiment... In various parts of the world there are River Bore's and high water flows through narrow channels between islands that are affected by tides that have to be challenged at slack water. So has anyone considered the merit of having both an inboard and and outboard running at the same time in these situations? or has the outboard proven too vulnerable to be useful in the very turbulent water.?

[Adelie]

Originally Posted by coastalexplorer

So much for Merlin engines in spitfires and failing bridges where did all that come from?...Many thanks for the back on topic comment about outboard swamping in the San Juan Islands.

They came out of related arguments and took on lives of their own briefly. Side discussion regularly occur in real life. Happens here to, just a little harder to tune out in print than in person. Actually the side discussion occasionally completely takes over the thread here and the original topic is completely lost.

Or did you think this would be a business meeting? Think again; in business meetings everybody is aware that time is money and there is a hierarchy to keep side discussions from being obtrusive. Neither one of those conditions apply here.

[SailingFan]

Originally Posted by coastalexplorer

So much for Merlin engines in spitfires and failing bridges where did all that come from?...Many thanks for the back on topic comment about outboard swamping in the San Juan Islands.

As stated previously we usually use a 2 horse power British Seagull Minus on the walker bay 8 which is perhaps immersed a bit deeper than the design specification due to crew weight...but with anchor, chain and Rode in the bow for safety and boat trim: we seem to get away with it. Also it is possible to adjust the distance between the propeller shaft and the clamping bracket on that one: though I have not bothered to do it yet.

During July we tried to transit through the Canal between the Pender Islands with the 2 hp heading west and had to bare off before passing under the bridge. We tried again and succeeded later in the day, So this is what prompted the curiosity thought to acquire the 4.5 horsepower British Seagull to try it out on the walker bay 8, I did not think the the additional 12 pounds difference between the two would be such a huge issue. (The adjustment of motor height on the Century model of 1963 vintage is not possible)

I conducted the test in the calm sheltered waters of the Deas Slough of the Fraser river. We had more push against wind and current, but no appreciable increase in speed. However the motor did not seem to be able to reach top revolutions possibly due the the immersion preventing the exhaust from escaping efficiently, thus causing an excessive back pressure. Back in the close proximity to the boat launch ramp Three power boats nearby heading in different directions churned up the water causing a partial swamping of the dinghy and the outboard motor died. Causing it to subsequently refuse to start. One of the ski boats seeing us using the oars towed us to the dock. The next day back at the workshop it started on test without any difficulty.

Thus I find the report of the problem in the San Juans islands interesting and possibly similar to my testing the 4.5 HP experiment... In various parts of the world there are River Bore's and high water flows through narrow channels between islands that are affected by tides that have to be challenged at slack water. So has anyone considered the merit of having both an inboard and and outboard running at the same time in these situations? or has the outboard proven too vulnerable to be useful in the very turbulent water.?

I have considered using just that method, the inboard AND the outboard at once, in higher currents and such, but still come back to the problem that two 8 HP engines do not add up to 16 HP and even if they did, it would not add up to much of a difference in speed since I would already be at or near hull speed with just the outboard alone (as we did just barely over 5 knots (like, 5.1 or 5.2 or some such) water speed several times with three inches of growth on the hull bottom during our transit to the St. John's via the ICW from Daytona.

I am unsure what the result would have been had the inboard been running at the same time, except that I doubt we would have had the cavitation issue when we were dealing with powerboat wakes (the only time there was a cavitation issue was in presence of these wakes). I think things would have been smoother with the inboard and with that larger prop, we would have had a little more speed, MAYBE... However, the boat was danged easy to maneuver at docks with the outboard. I just don't know if the second engine at the same time would have given us any more useful thrust than we already had, at least not as it would have been realized on a GPS or log unit. I am all ears if someone has more experience with that particular issue (our H27 hull speed should be something like 6.8 knots).

[StuM]

Cats with two props which are widely separated laterally and in relatively undisturbed water can get benefits from running two engines.

On a monohull with an outboard operating in the disturbed wake just behind an inboard engine, I suspect it would have limited benefit.

[Cadence]

Originally Posted by StuM

Cats with two props which are widely separated laterally and in relatively undisturbed water can get benefits from running two engines.

On a monohull with an outboard operating in the disturbed wake just behind an inboard engine, I suspect it would have limited benefit.

Beats crabbing.

[Goosebumps]

Outboard mounted at stern can submerge because of hobbyhorsing in extreme conditions. I am much in favor of inboard diesels, for the many reasons like diesel less dangeroys than gasoline stored, transported... charging of batteries with high rate alternators advantage even in conjunction with solar charging. I also value outboards tough fir the right use. The hobbyhorsing was not a problem on my Tiki 30 which had a designated outboard motor well about 2 meter from stern. With a Johnson 15hp four stroke this was a real good set up and that outboard gave fair amount of charge to batteries too. I was in extreme weather with it, bare poled, huge waves, but outboard kept going allowing me to steer Tiki in huge waves. To me two stroke outboards are best for use on yacht fir dinghy and emergency powering of yacht, towing with dinghy or even mounting on stern yacht. The stirage if small amount of gasoline can be safe in dedicated ventilated compartment, ie on cat ventilating between hulls under deck.

[thomm225]

I actually only planned to use my engine (outboard) to come and go from the slip when first getting into this monohull business after owning and racing 4 different beach cats which don't have engines.

This over a 15 year period.

Racing beach cats on the gulf coast was a bit different though than at many inland venues because we had multiple distance races on the schedule of between 30 and 100 miles both along the ICW and out in the Gulf

This prepares you to not depend on your engine even when entering and exiting a pass or inland with little wind and lots of current.

The jetty near Destin though can be a worry though with no wind, no anchor, and lots of current

After sailing the monohull for a couple years and "wasting" several hours waiting on the wind to cross the bay, I finally started using the outboard to make way toward my destination even though I would burn a whole gallon of gas or so.

The engine does have a way of spoiling you where before we had no choice because there was no engine on the boat.

If you didn't complete the 100 mile race before dark, you kept sailing if you had wind otherwise you drifted. I still remember taking a nap and star watching at 1 am with 20 miles still to go and no wind in the ICW