poor power in reverse

Just bought a sailboat with a 1982 7.5 hp mercury-had it serviced/tuned up by local mercury shop-runs fine in forward, but in reverse prop is seen turning but very little power to actually move the boat backwards (to get out of the slip)
I read in another post about a similar problem with the suggestion that "a rubber donut inside the hub being "spun out" -any thoughts/observations appreciated hrsailor2

Re: poor power in reverse

Hi,

Unless it has a special sailboat prop on it they have very little reverse thrust on the std fishing prop. So I am guessing you would need a different prop.

Re: poor power in reverse

corm said:

Hi,

Unless it has a special sailboat prop on it they have very little reverse thrust on the std fishing prop. So I am guessing you would need a different prop.

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Thanks for your reply. The motor (long shaft-electric start) is on a spring loaded mount-when down, the propellor hub is 15 inches below the water surface so hopefull that's deep enough. Any hints you have on how to determine if it's a standard prop and where to find alternatives is appreciated. Bob B

Re: poor power in reverse

Hi,

I did a search for prop pictures and came up empty.
If your engine does not say Sailor on the hood chances are you do not have a sailor prop on it. Merc used to make a version of that motor for the wind guys. I doubt you can buy a new sailor reverse thrust prop from a Merc Dealer
anymore. My guess as to what is happening is that the ehaust gases are exiting out the prop hub and causing a little cavitation around the prop blades. So you will not get much bite with the blades in the water. Your depth is fine, even the set-up sounds good. If you are able look down at the prop while you are running it. You should be able to see the exhaust coming out around the prop. You should have a 3 bladed prop with a pitch of 7" on the engine. That was the std prop from the factory. I would check with a Merc Dealer to se if you can still get a Sailor prop for the little Merc. It never hurts to check.

Mercury had a Service Buliton on drilling a hole in the ehaust housing for back trolling that may help you out with your thrust problem. Drilling the hole will increase the exhaust noise on your set-up. Something you may not like.