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Author Topic:   Raising my 70HP Evinrude on my 15 SS

grosseile88 posted 09-28-2010 04:49 PM ET (US)
I have a 1985 Envinrude 70 HP on my 15 SS. It is currently mounted all the way down on the transom and I would like to raise it to improve performance. Its plenty fast now but I think it would perfrom even better. The top transom bolts are exposed inside and out of transom. The lower bolts can only be seen from inside. Can I take off the top bolts, loosen the lower boats and expect the engine to be able to be raised up to the a higher hole? I am not sure the bolts that I can only see from inside of lower transom are able to slide up or down or if I am missing something all together??? Also the motor has a hyro foil on the cavitation plate that I think just slows me down and I am leaning towards taking it off. Any thoughts??
Thanks for the help!
Sean
tedious posted 09-28-2010 05:28 PM ET (US)
Sean, your motor is mounted using the "blind holes" that go through the transom into a threaded hole in the motor bracket. It cannot be raised without filling and redrilling the lower holes, and replacing the lower bolts and nuts. You may wish to read bulletin 84-10 in the reference section here.
Since your motor is all the way down, with the anti-ventilation plate well below the keel, the hydrofoil is costing you some speed. If absolute minimum planing speed is your only goal, then keep it. My personal feeling is that these fins are a solution looking for a problem.
I can tell you from experience that the boat performs better with the motor "two holes up" especially if you have a good prop.
Tim
Tohsgib posted 09-29-2010 12:29 AM ET (US)
Fill and move up or buy a $17- jackplate. I would HIGHLY recommend the plate. Not only do you move it up but you enhance performance by setting it back.
Tohsgib posted 09-29-2010 09:55 AM ET (US)
Sorry I meant $175.
grosseile88 posted 09-29-2010 12:13 PM ET (US)
Thanks for the input. Do you reccomend a specific jack plate and will it fit my existing holes.
Thanks again!
Sean
dgoodhue posted 09-29-2010 02:12 PM ET (US)
You will have to drill the Jackplate to fit your 2 blind hole locations.
dgoodhue posted 09-29-2010 02:20 PM ET (US)
I have a Bob's Machine 4-1 Convertible Jackplate, I like it a lot.
http://continuouswave.com/ubb/Forum3/HTML/018119.html
Here is a few picture of the Jackplate on my 15' SS.
http://s202.photobucket.com/albums/aa177/sytydave/Boston%20Whaler/ Jackplate/
grosseile88 posted 09-29-2010 02:49 PM ET (US)
Thanks for the advice, yours came out great and does not seem like that much of a hassle to install. I like the fact that you can trailer the boat with the engine in the vertical position, added bonus.
dgoodhue posted 09-29-2010 08:29 PM ET (US)

quote:
I like the fact that you can trailer the boat with the engine in the vertical position, added bonus.
I wouldn't trailer it with the motor down. I actually lightly bumped the skeg getting out of the driveway with the motor down much to my surprise (my father was watching and let me know).
grosseile88 posted 05-13-2011 11:18 AM ET (US)

Thanks for all the input. I am getting ready to pull the trigger on a CMC manual jack plate with 5.5" of set back. I like the Bob's jack plate but it appears if you look at page 3 of the installation manual below that I can mount the CMC with the existing pre drilled bolt holes on the plate and with the Bob's plate I would have to drill the plate since my current engine is a 70HP Evinrude with the blind hole set up. Am I looking at this right? If someone has a similar set up let me know. Thanks!
http://cook-mfg.net/PDFs/PL-65%20Owners%20Manual.pdf
Tohsgib posted 05-13-2011 02:21 PM ET (US)
Does not really matter. Drilling the plate to match your bottom holes takes 2 minutes.
dscew posted 05-13-2011 02:34 PM ET (US)
I had to drill my CMC 4" manual setback plate to match the holes in the transom, but unlike Tohsgib's it took 4 minutes. It is a very nice setup on my 1974 Katama/60 HP Merc.
grosseile88 posted 05-13-2011 02:44 PM ET (US)

Thanks! Thought I might need a drill press but sounds like it is easy, take it you guys used standard drill? If so I will try to beat Tohsgib's record!
dscew posted 05-13-2011 04:40 PM ET (US)
I did use a drill press, but aluminum is soft and you'll be able to get through it with a hand-held drill easily. It was probably setting up the drill press that doubled Tohs's time for me.
dgoodhue posted 05-13-2011 07:19 PM ET (US)
I used a hand drill.
grosseile88 posted 05-16-2011 10:25 AM ET (US)
Did you guys have to lengthen steering cable? I think I can find the slack but dont want to come up 1/2" short!!
Thanks
dgoodhue posted 05-16-2011 11:11 AM ET (US)
My steering cable fit I just had to the corner and go in front of the light.
Tohsgib posted 05-16-2011 02:14 PM ET (US)
Actually it probably took less than 2 minutes. I mounted the plate using the top bolts and used a 90degree air drill going right through the transom holes into the plate. Maybe 45sec-1minute without drill and air hose setup time ;)

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Author	Topic: Raising my 70HP Evinrude on my 15 SS
grosseile88	posted 09-28-2010 04:49 PM ET (US) I have a 1985 Envinrude 70 HP on my 15 SS. It is currently mounted all the way down on the transom and I would like to raise it to improve performance. Its plenty fast now but I think it would perfrom even better. The top transom bolts are exposed inside and out of transom. The lower bolts can only be seen from inside. Can I take off the top bolts, loosen the lower boats and expect the engine to be able to be raised up to the a higher hole? I am not sure the bolts that I can only see from inside of lower transom are able to slide up or down or if I am missing something all together??? Also the motor has a hyro foil on the cavitation plate that I think just slows me down and I am leaning towards taking it off. Any thoughts?? Thanks for the help! Sean
tedious	posted 09-28-2010 05:28 PM ET (US) Sean, your motor is mounted using the "blind holes" that go through the transom into a threaded hole in the motor bracket. It cannot be raised without filling and redrilling the lower holes, and replacing the lower bolts and nuts. You may wish to read bulletin 84-10 in the reference section here. Since your motor is all the way down, with the anti-ventilation plate well below the keel, the hydrofoil is costing you some speed. If absolute minimum planing speed is your only goal, then keep it. My personal feeling is that these fins are a solution looking for a problem. I can tell you from experience that the boat performs better with the motor "two holes up" especially if you have a good prop. Tim
Tohsgib	posted 09-29-2010 12:29 AM ET (US) Fill and move up or buy a $17- jackplate. I would HIGHLY recommend the plate. Not only do you move it up but you enhance performance by setting it back.
Tohsgib	posted 09-29-2010 09:55 AM ET (US) Sorry I meant $175.
grosseile88	posted 09-29-2010 12:13 PM ET (US) Thanks for the input. Do you reccomend a specific jack plate and will it fit my existing holes. Thanks again! Sean
dgoodhue	posted 09-29-2010 02:12 PM ET (US) You will have to drill the Jackplate to fit your 2 blind hole locations.
dgoodhue	posted 09-29-2010 02:20 PM ET (US) I have a Bob's Machine 4-1 Convertible Jackplate, I like it a lot. http://continuouswave.com/ubb/Forum3/HTML/018119.html Here is a few picture of the Jackplate on my 15' SS. http://s202.photobucket.com/albums/aa177/sytydave/Boston%20Whaler/ Jackplate/
grosseile88	posted 09-29-2010 02:49 PM ET (US) Thanks for the advice, yours came out great and does not seem like that much of a hassle to install. I like the fact that you can trailer the boat with the engine in the vertical position, added bonus.
dgoodhue	posted 09-29-2010 08:29 PM ET (US) quote: I like the fact that you can trailer the boat with the engine in the vertical position, added bonus. I wouldn't trailer it with the motor down. I actually lightly bumped the skeg getting out of the driveway with the motor down much to my surprise (my father was watching and let me know).
grosseile88	posted 05-13-2011 11:18 AM ET (US) Thanks for all the input. I am getting ready to pull the trigger on a CMC manual jack plate with 5.5" of set back. I like the Bob's jack plate but it appears if you look at page 3 of the installation manual below that I can mount the CMC with the existing pre drilled bolt holes on the plate and with the Bob's plate I would have to drill the plate since my current engine is a 70HP Evinrude with the blind hole set up. Am I looking at this right? If someone has a similar set up let me know. Thanks! http://cook-mfg.net/PDFs/PL-65%20Owners%20Manual.pdf
Tohsgib	posted 05-13-2011 02:21 PM ET (US) Does not really matter. Drilling the plate to match your bottom holes takes 2 minutes.
dscew	posted 05-13-2011 02:34 PM ET (US) I had to drill my CMC 4" manual setback plate to match the holes in the transom, but unlike Tohsgib's it took 4 minutes. It is a very nice setup on my 1974 Katama/60 HP Merc.
grosseile88	posted 05-13-2011 02:44 PM ET (US) Thanks! Thought I might need a drill press but sounds like it is easy, take it you guys used standard drill? If so I will try to beat Tohsgib's record!
dscew	posted 05-13-2011 04:40 PM ET (US) I did use a drill press, but aluminum is soft and you'll be able to get through it with a hand-held drill easily. It was probably setting up the drill press that doubled Tohs's time for me.
dgoodhue	posted 05-13-2011 07:19 PM ET (US) I used a hand drill.
grosseile88	posted 05-16-2011 10:25 AM ET (US) Did you guys have to lengthen steering cable? I think I can find the slack but dont want to come up 1/2" short!! Thanks
dgoodhue	posted 05-16-2011 11:11 AM ET (US) My steering cable fit I just had to the corner and go in front of the light.
Tohsgib	posted 05-16-2011 02:14 PM ET (US) Actually it probably took less than 2 minutes. I mounted the plate using the top bolts and used a 90degree air drill going right through the transom holes into the plate. Maybe 45sec-1minute without drill and air hose setup time ;)