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Catalina/Capri 25/250 Sailor's Forums

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Outboard in Reverse

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sanibelle36
Deckhand

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USA
3 Posts

Initially Posted - 07/01/2002 : 22:43:12

Hi Guys,

My 1980 fin keel tall rig has a brand new OMC 9.9HP.
The boat moves fine ahead, takes a very long time to begin moving in reverse (I'm talking about dead calm situations). Is this normal? Can anyone suggest a remedy.

Also, even with the spring loaded motor bracket, raising the motor out of the water still gives my back a problem. Is there a way to make this job easier on this old man's back?

Would appreciate any inputs.

Joe Russo

Edited by - on

eric.werkowitz
Captain

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USA
283 Posts

Response Posted - 07/01/2002 : 23:22:19

I can't advise whether your moving in reverse is abnormally slow or not, but as for lifting the motor: try using a small block attached to the mount handle and running a line from the rear pulpit rail to the block and back to the rail. This will not only give a two-to-one purchase, but improves the lift angle on the old back. Actually, I don't even use a block, I just run the line from the pulpit rail to the handle and back. Grabbing either end and pulling achieves the same effect, but with a little more friction.

Eric Werkowitz
C25 #4969

Edited by - eric.werkowitz on 07/01/2002 23:23:52

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dlucier
Master Marine Consultant

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Virgin Islands (United Kingdom)
7583 Posts

Response Posted - 07/01/2002 : 23:39:36

"The boat moves fine ahead, takes a very long time to begin moving in reverse (I'm talking about dead calm situations). Is this normal?" - Joe Russo

Yes, it is normal. Firstly, you must keep in mind the prop and the lower unit are designed for efficient operation in only one direction, forward. That means that when backing up, both the prop and hull are now operating in the least efficient direction, so the going is going to be slower. Secondly, you may want to check that the prop is at the proper depth and that the motor is trimmed correctly. If the motor is trimmed up, it maybe trying to pull the stern in an upward direction instead of directly aft thereby wasting horsepower and decreasing what little efficiency you have.

Concerning your other question about the outboard bracket, I've read that some people have purchased another spring from Home Depot and installed it on the brackets to give them an extra boost. Click on the link below to see an article in the Tech Tips section concerning this modification.
http://c25c250.best.vwh.net/restricted/cokie.html

Don Lucier, North Star
C25 SR/FK

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dgabel
1st Mate

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USA
75 Posts

Response Posted - 07/02/2002 : 17:51:44

I have a Nissan 9.9 that proved very difficult to lift. I solved it by instaling a double block on the engine handle, and a double block with becket on the stern rail. Then I put a single stand-up block on the top of the transom, and a cleat a short distance away. I use 1/4-in. line starting at the becket to hook the whole thing up. I wouldn't say it's easy now, but it's a lot easier than it was. And the line acts as a safety line when the engine is either up or down, should the mount break.

Dave Gabel
Walkure
'78 Cat 25 fin keel hull 1484

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Douglas
Master Marine Consultant

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1595 Posts

Response Posted - 07/02/2002 : 18:30:46

Take a good look at the prop, think about it for a minute. The pitch of the prop is designed to give maximum or high thrust in the forward position. When its placed into reverse not only is it turning backwards from design intent its cavitating and sucking in all the exaust. I think what you are seeing is normal.

Doug&Ruth
Wind Lass
Tacoma Wa.

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Steve Milby
Past Commodore

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USA
5902 Posts

Response Posted - 07/02/2002 : 20:29:08

Douglas,

I have a 23 year old Merc 7.5 hp long shaft outboard. The exhaust comes out through the propeller hub. Like you, I believe that, in reverse, the exhaust gasses cause the prop to cavitate, and that degrades the ability of the motor to drive the boat in reverse.

When the motor was new, I drilled a 3/8" hole through both sides of the lower unit housing to allow much of the exhaust gas to escape to both sides, rather than through the propeller hub. Although I have no way of proving it objectively, my sense is that it has improved the amount of drive that my motor has in reverse. After all these years, it has not harmed the motor in any way that is apparent.

Steve Milby "Captiva Wind" C-25 T/FK #2554

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Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 07/02/2002 : 23:08:34

Exhaust around the prop is one problem, and the standard propeller on most outboards is the other. The high-pitch standard prop is designed to push a small boat at a high speed. On a big, heavy, displacement hull, it acts somewhat like a paddle wheel, trying to push sideways almost as much as backward--causing the "prop walk" that pushes the transom to starboard and pulls it (backing up) to port.

I have noticed a great deal of difference with the low-pitch, "high thrust" prop on our new Honda--less prop walk, and much faster starting and stopping. Other things that might help are that in reverse, the exhaust vents away from the prop, and the longer shaft puts the prop about 6" deeper. Cruising speed does require slightly higher RPMs.

I'd suggest you talk to your OMC/Bombardier dealer about a lower pitch, larger diameter prop--possibly a 4-blader--the largest that will fit under the plate and won't reach below the skeg. I don't know about drilling holes--water may not do that well with the gear oil, and vice versa.

Dave Bristle - 1985 C-25 #5032 SR-FK-Dinette "Passage" in SW CT

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The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.