Setback for Vector/Merc 115


My Sons and I are restoring an ‘81 Vector.  We will be rigging it with a 1984 Merc 115 inline six.  The boat is going to be used for general "hot rodding" with two 170#  pilot/co-pilot.  16 gal gas tank and battery in back.

How much setback would you recommend for the 115 on this set up?

Thanks for your help and for your contribution to the Hydrostream Registry!



If you are going to use the boat for hot rodding, set the motor on the transom. It has a 23” transom height already and setting the motor back will just make it porpoise in the mid range speeds. Find yourself a 14 x 22 small ear (or inline) chopper and have a good prop shop put some acceleration roll in it. This would be the most fun. If you set the motor back and jack it up, you will need a 24” prop as it will slip more with the limited power you have. Then your punch will suffer and the “fun factor” will be less. Either set up will top out in the mid 60’s, so I would go for the punchier of the two. Also, if your motor has the trim system with the remote pump and the 2 trim rams on the outside of the clamp brackets, a jackplate is a tough fit.




Please submit whatever questions you have to  All questions and answers selected will be displayed on this page as they come in.  Note: though all boaters are welcome, priority may be given to I.H.R. members.  Randy can not be held responsible for any advice given.  Though his information and expertise is second to none, he has no control over what you do with your boat.  It is up to you to boat safely and act responsibly, and his advice is only to be used as a guidance for your high performance boat/motor of which you are the one responsible for the risks involved.

Mark C.


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