interesting hydrofoil true batwing

[tashasdaddy]

saw this on ebay, 1959 Arkansas Traveler w/ 18 hp, this must be an original design.

 

[xtraham]

Re: interesting hydrofoil true batwing

I have one just like it........8)

 

[steelespike]

Re: interesting hydrofoil true batwing

Hard to tell but it appears the motor is about 3 inches too low.

 

[Paul Moir]

Re: interesting hydrofoil true batwing

That's fairly normal for those engines - the measure about 18" to the anti-ventilation plate so (I suppose) the reverse intake above the water line and so the pump is submerged at idle.
Which is why hydrofoils are never a good idea on older 60s era Johnny/Rudes.

 

[Texasmark]

Re: interesting hydrofoil true batwing

Interesting, not trying to change the subject, buttttt.

I just sent a question to Mr. D Hadley on Outboard Non Repair discussions questioning just what you see in this picture.

Maybe Paul you hit the nail on the head. Since the water intake was in the front section of the exhaust deflector, you needed to have that intake submerged when running to get cooling.....so OMC in particular made the skeg longer to insure it was submerged when running.

Nowadays, with the water intakes on the sides of the lower units, they get adequate cooling water with the plate mounted higher.

What do you think?

Mark

 

[Paul Moir]

Re: interesting hydrofoil true batwing

See that cover just above the anti-ventilation plate on the side of the lower unit? You can just see one of the two screws holding it on. That plate covers the water passage that connects the water intake on the front of the exhaust "fin" to the water pump.

That cover has holes drilled in it to to allow water into that passage. The idea is, water will not go into the normal intake when in reverse I suppose because of exhaust bubbles and suction from the propeller. So water can get in through that cover. Naturally that cover must be submerged when the engine is in neutral or reverse. In forward water is being forced into the intake by the propeller so it's not a problem.

An additional issue is that water pumps on these older J/E engines would not self-prime if dry. They had to be submerged at start up. I think the big problem there was the lack of a driveshaft seal on the water pump.

I don't understand the exact advantages, but it seems to me this sort of setup is present on all non thru-hub exhaust engines. Even the later (00s) J/E 6hp engines had that reverse intake. Perhaps it a necessity of the casting process used.

 

[Texasmark]

Re: interesting hydrofoil true batwing

Boy that was quick. Almost like live chat!

I learned what you said about submerged impellers the hard way. I used to run small engines in a 55 gallon drum and after running in gear for a bit, I'd splash out a lot of water. Once I kicked the engine out of gear, it quit cooling.....forget how I detected that fact since they had no pee stream at the time.....may have been smell d .

Other no-no I used to do was to run the engine out of the water. Can't imagine what my impellers looked like then as I didn't know anything about impellers and all that stuff. Had I known, I surely wouldn't have run them dry.....course, once I got the faith, I quit it. d

I am familiar with the plate on the side of which you speak. Didn't realize that it was for N and R operation. Does make sense however, once you mentioned it. Do recall every time I'd pull an engine out of the drum water would exit there....makes sense, coming from the wp inlet.

I really didn't like that F water pickup tube. We operated in shallow coastal lagoons and the propwash was always full of sand or mud or some abrasive that had to drive the impeller nuts.

Mark