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Author Topic:   CMC PT-35 Engine Height on Classic 13

tmann45 posted 07-17-2011 12:22 AM ET (US)
I'm planning the installation of the CMC power tilt on my 1986 13. The current engine is a 1986 Mercury 35 without power tilt and trim. My motor and transom are both 20".
The installation manual says to install the motor 1-3 inches higher due to the 5.5 inches of setback, good so far. One problem is once the bracket is mounted, if the motor is too high, it could require more holes to be drilled in the transom. I want to avoid drilling more holes in the transom than necessary.
The bracket has the motor mounting part of the bracket 3-11/16 higher than the original transom measured parallel to the bracket. With the angle of the transom being 15-20 degrees, the actual set back and new mounting height can be calculated.
However, what can be calculate does not always work out in the real world. So, does anyone have any experience with a CMC PT-36 installed on a 13 with a 20" motor and transom?
Was it mounted as per the instructions with the motor 3-11/16" higher (not accounting for transom angle) than the original transom?
How was performance? Did you have ventilation problems? Did the motor seem to mounted at the proper height? Do you wish it was mounted higher or lower?
Tom
pcrussell50 posted 07-17-2011 09:15 PM ET (US)
For my 1985 classic 13, I am considering going this route myself, altough it's pretty far down my priority list, because the 1985 Yamaha 40hp is so very easy to tilt by hand, and with the hooked hull, I preset the tilt pin to a good angle for cruising, and it still blasts right up onto plane without any nose-high, histrionics.
That said, I'm a big fan of CMC trim/tilt brackets. I have the bigger one, PT130, on one of my fast lake boats with a bubbleback v4. Super clean installation and operation.
[URLhttps://picasaweb.google.com/pcrussell50/Tahiti#5408905886100710866[/URL]
Ok, to your question, I'm not sure I get it. If you mount the CMC bracket flush with the top of the transom, you can then mount your motor with the anti-ventilation plate even with the bottom of the keel, (or even higher), in it's [Ilowest[/I] setting, and move it up from there as desired, using the holes in the engine's transom bracket.
-Peter
pcrussell50 posted 07-17-2011 09:16 PM ET (US)
https://picasaweb.google.com/pcrussell50/Tahiti#5408905886100710866
-Peter
Tohsgib posted 07-18-2011 01:03 PM ET (US)
Peter moving the engine height with twist clamps is not an option.
I had the PT130 on my 13 mounted pretty close to flush or max 1" below. I also had the engine raised up 2 holes on the bracket. My cav plate was a good 4" above the keel. My current Suzuki 40hp 4 stroke is mounted sans bracket(I have enough weight) and she is mounted ALL the way up(3"+) and handles perfect. Does the PT35 mpount with the now standard BIA mounting holes or is it whacked? If BIA then find out where that should be mounted and do that and you should be golden. If Not BIA then find out where BIS should be mounted(1-2" from top) and mount it there, etc.
Hell I'll go measure where my top holes are......CENTER of bolt is 2" below the top of the transom.
pcrussell50 posted 07-18-2011 01:33 PM ET (US)
He has twist clamps? Whoops. Didn't know or assume that.
-Peter
tmann45 posted 07-18-2011 03:32 PM ET (US)
Thanks for the input Peter and Nick.
I just did the calculations. Using a 20-degree transom angle the setback becomes 6.4 inches and the lift becomes only 1.6 inches. Using a 15-degree transom angle the setback becomes 6-1/4 inches and the lift becomes 2-1/8 inches. So the original 3-11/16 inches of lift that I was worried about is greatly reduced by the transom angle.
Yes, twist clamps, and hard to raise and lower without drilling more holes.
No, bracket is not BIA, transom holes will be spaced 8.5" vertically and 7-7/8" horizontally. Motor holes are drill your own.
I think mounting according to the instructions with the above calculated setback and lift should be ok.
Tohsgib posted 07-18-2011 11:36 PM ET (US)
If anyway to mount using BIA...use it for future repowers. If not then repower with a smaller engine and continue with the PT35 and save $500 on the PTnT option. You really can't go too low so maybe you should go higher than you think. Again if it is close to flush or 1" or so from the transom, you should be fine.
Tohsgib posted 07-18-2011 11:45 PM ET (US)
Not a great example but you can see where I am on the transom and where the clamps should have been. http://img.photobucket.com/albums/v225/BiggieFL/1981-13Whaler/015-1.jpg
I am mounted BIA with the bolts 2" centered from top of transom. You can "pretty" much lay it on the transom with the bottom holes so I am 3" up or so.
tmann45 posted 07-19-2011 09:48 AM ET (US)

quote:
If anyway to mount using BIA...use it for future repowers.

I wish I could for future repower but no way, the bracket is only 10-3/4" wide, BIA is 12-7/8" for top holes. I'll just deal with the 2 old holes now and 4 more in the future.
tjxtreme posted 07-19-2011 11:31 AM ET (US)
Here is a CMC PT 35 on my 13'
http://i1022.photobucket.com/albums/af349/tjxtreme/CMC%20PT%2035/photo7. jpg
One thing that simplifies the calculations, for better or worse, is that there is really only one position to mount the CMC unit... the space between the transom top and the drain hole leaves little room for adjustment.
That being said, it works great on mine. I'm not really a performance geek though, just a fishing geek.
tjxtreme posted 07-19-2011 11:37 AM ET (US)
Also, I see you are in Louisiana- I'm in Baton Rouge so you are welcome to come check it out.
Tohsgib posted 07-19-2011 11:44 AM ET (US)
That is one reason I recommend the PT130 for a few bucks more but it is a tad heavier.
Good point with the drain tube, etc. I guess sometimes it is better to just try and mount it and not read the instructions...oh wait...I already do that....I'm a man!
Directions!...we don't need no stinkin DIRECTIONS!
tmann45 posted 07-19-2011 11:12 PM ET (US)
tj, thanks for heads up on the drain and the picture. I might take you up on the visit but it will be a couple of months. Yours looks great with that new Yamaha on it.
tmann45 posted 01-24-2012 10:52 PM ET (US)
Finally getting around to mounting the PT-35. It appears that if mounted at the recommended height, the top bolts will come out at the very top edge of the inside transom.
tjx, do you have another picture that shows the top bolts inside the transome on yours? It looks like you are mounted at the recommended height, 1" up?
Tohsgib posted 01-25-2012 02:49 PM ET (US)
Go with the recommended height but bring it down so they have something to bite.
tjxtreme posted 01-25-2012 02:58 PM ET (US)
http://i1022.photobucket.com/albums/af349/tjxtreme/CMC%20PT%2035/photo9. jpg
Here is the view from the inside of the transom. Its close, but there is still plenty of wood up there.
tmann45 posted 01-25-2012 06:03 PM ET (US)
Thanks for the picture, just what I wanted.

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Author	Topic: CMC PT-35 Engine Height on Classic 13
tmann45	posted 07-17-2011 12:22 AM ET (US) I'm planning the installation of the CMC power tilt on my 1986 13. The current engine is a 1986 Mercury 35 without power tilt and trim. My motor and transom are both 20". The installation manual says to install the motor 1-3 inches higher due to the 5.5 inches of setback, good so far. One problem is once the bracket is mounted, if the motor is too high, it could require more holes to be drilled in the transom. I want to avoid drilling more holes in the transom than necessary. The bracket has the motor mounting part of the bracket 3-11/16 higher than the original transom measured parallel to the bracket. With the angle of the transom being 15-20 degrees, the actual set back and new mounting height can be calculated. However, what can be calculate does not always work out in the real world. So, does anyone have any experience with a CMC PT-36 installed on a 13 with a 20" motor and transom? Was it mounted as per the instructions with the motor 3-11/16" higher (not accounting for transom angle) than the original transom? How was performance? Did you have ventilation problems? Did the motor seem to mounted at the proper height? Do you wish it was mounted higher or lower? Tom
pcrussell50	posted 07-17-2011 09:15 PM ET (US) For my 1985 classic 13, I am considering going this route myself, altough it's pretty far down my priority list, because the 1985 Yamaha 40hp is so very easy to tilt by hand, and with the hooked hull, I preset the tilt pin to a good angle for cruising, and it still blasts right up onto plane without any nose-high, histrionics. That said, I'm a big fan of CMC trim/tilt brackets. I have the bigger one, PT130, on one of my fast lake boats with a bubbleback v4. Super clean installation and operation. [URLhttps://picasaweb.google.com/pcrussell50/Tahiti#5408905886100710866[/URL] Ok, to your question, I'm not sure I get it. If you mount the CMC bracket flush with the top of the transom, you can then mount your motor with the anti-ventilation plate even with the bottom of the keel, (or even higher), in it's [Ilowest[/I] setting, and move it up from there as desired, using the holes in the engine's transom bracket. -Peter
pcrussell50	posted 07-17-2011 09:16 PM ET (US) https://picasaweb.google.com/pcrussell50/Tahiti#5408905886100710866 -Peter
Tohsgib	posted 07-18-2011 01:03 PM ET (US) Peter moving the engine height with twist clamps is not an option. I had the PT130 on my 13 mounted pretty close to flush or max 1" below. I also had the engine raised up 2 holes on the bracket. My cav plate was a good 4" above the keel. My current Suzuki 40hp 4 stroke is mounted sans bracket(I have enough weight) and she is mounted ALL the way up(3"+) and handles perfect. Does the PT35 mpount with the now standard BIA mounting holes or is it whacked? If BIA then find out where that should be mounted and do that and you should be golden. If Not BIA then find out where BIS should be mounted(1-2" from top) and mount it there, etc. Hell I'll go measure where my top holes are......CENTER of bolt is 2" below the top of the transom.
pcrussell50	posted 07-18-2011 01:33 PM ET (US) He has twist clamps? Whoops. Didn't know or assume that. -Peter
tmann45	posted 07-18-2011 03:32 PM ET (US) Thanks for the input Peter and Nick. I just did the calculations. Using a 20-degree transom angle the setback becomes 6.4 inches and the lift becomes only 1.6 inches. Using a 15-degree transom angle the setback becomes 6-1/4 inches and the lift becomes 2-1/8 inches. So the original 3-11/16 inches of lift that I was worried about is greatly reduced by the transom angle. Yes, twist clamps, and hard to raise and lower without drilling more holes. No, bracket is not BIA, transom holes will be spaced 8.5" vertically and 7-7/8" horizontally. Motor holes are drill your own. I think mounting according to the instructions with the above calculated setback and lift should be ok.
Tohsgib	posted 07-18-2011 11:36 PM ET (US) If anyway to mount using BIA...use it for future repowers. If not then repower with a smaller engine and continue with the PT35 and save $500 on the PTnT option. You really can't go too low so maybe you should go higher than you think. Again if it is close to flush or 1" or so from the transom, you should be fine.
Tohsgib	posted 07-18-2011 11:45 PM ET (US) Not a great example but you can see where I am on the transom and where the clamps should have been. http://img.photobucket.com/albums/v225/BiggieFL/1981-13Whaler/015-1.jpg I am mounted BIA with the bolts 2" centered from top of transom. You can "pretty" much lay it on the transom with the bottom holes so I am 3" up or so.
tmann45	posted 07-19-2011 09:48 AM ET (US) quote: If anyway to mount using BIA...use it for future repowers. I wish I could for future repower but no way, the bracket is only 10-3/4" wide, BIA is 12-7/8" for top holes. I'll just deal with the 2 old holes now and 4 more in the future.
tjxtreme	posted 07-19-2011 11:31 AM ET (US) Here is a CMC PT 35 on my 13' http://i1022.photobucket.com/albums/af349/tjxtreme/CMC%20PT%2035/photo7. jpg One thing that simplifies the calculations, for better or worse, is that there is really only one position to mount the CMC unit... the space between the transom top and the drain hole leaves little room for adjustment. That being said, it works great on mine. I'm not really a performance geek though, just a fishing geek.
tjxtreme	posted 07-19-2011 11:37 AM ET (US) Also, I see you are in Louisiana- I'm in Baton Rouge so you are welcome to come check it out.
Tohsgib	posted 07-19-2011 11:44 AM ET (US) That is one reason I recommend the PT130 for a few bucks more but it is a tad heavier. Good point with the drain tube, etc. I guess sometimes it is better to just try and mount it and not read the instructions...oh wait...I already do that....I'm a man! Directions!...we don't need no stinkin DIRECTIONS!
tmann45	posted 07-19-2011 11:12 PM ET (US) tj, thanks for heads up on the drain and the picture. I might take you up on the visit but it will be a couple of months. Yours looks great with that new Yamaha on it.
tmann45	posted 01-24-2012 10:52 PM ET (US) Finally getting around to mounting the PT-35. It appears that if mounted at the recommended height, the top bolts will come out at the very top edge of the inside transom. tjx, do you have another picture that shows the top bolts inside the transome on yours? It looks like you are mounted at the recommended height, 1" up?
Tohsgib	posted 01-25-2012 02:49 PM ET (US) Go with the recommended height but bring it down so they have something to bite.
tjxtreme	posted 01-25-2012 02:58 PM ET (US) http://i1022.photobucket.com/albums/af349/tjxtreme/CMC%20PT%2035/photo9. jpg Here is the view from the inside of the transom. Its close, but there is still plenty of wood up there.
tmann45	posted 01-25-2012 06:03 PM ET (US) Thanks for the picture, just what I wanted.