Whaler Central - Boston Whaler Boat Information and Photos

Posted by joninnj on 05/01/08 - 4:11 AM

Hi all,

Has anyone installed a jack plate on a pre 2002 (smirked) 17 footer? I am looking to do this but I am concerned that the plate will be to wide. The drain for the well is only about an 1 1/2 inches from the mounting for engine today. The jack plates seems to be about an inch and half wider than the engine. It could cover part of the drain... and not sit flush on the transom... I have 90 HP Yamaha. Generally speaking I believe most engines use a standard bolt pattern.

Any thoughts?

Thx

Posted by Pete on 05/01/08 - 11:30 AM

I put a 4" CMC 2 piece plate on my 1984 Montauk w/ 1984 90 Johnson. I also have a 8 hp kicker mounted in the stern. I did not get a noticible perf gain. The plate did just clear both drain holes. To replace the drain tubes in the future you would need to remove the engine and take apart the plate. My engine was mounted in the engine lowest position. - hole 1 very top of the bracket. As already noted the plate would fit the standard engine pattern but not in my case since the engine was bolted in the top hole and bottom into the fixed threads on the engine bracket. With this plate I needed to drill new bottom holes (in the plates) to mount to the existing transom holes. The engine then bolted to the existing plate holes. My montauk now sat a bit lower in the water at the stern at rest. When I stepped in there was a a big diff of 2" lower in the stern.
Following sea, reverse, onshore wind at the ramp.....all a problem. My fav is the on shore wind at the ramp. A few small waves and 6"+ water in the boat before I stepped in - sends the kids into panic........ I was able to eliminate the Doel fin and had no porpoising. I did try a 21, 19, 18 and 17" prop but got no more speed (40 mph) than originally with the 21 OMC prop no mater what height setting.
I removed the plate and drilled 2 new bottom holes in the transom and raised my engine. I gained 200 rpm - same top end - great plane and hole shot - no doel fine.
Good luck.

Posted by joninnj on 05/02/08 - 4:25 AM

Thanks Pete,

I am pretty sure my engine is also bolted to the threaded connections on the lower section. I guess there was no hole drilled in that spot on the CMC plate?

Did you consider drilling into the plate? How did this prevent you from raising the engine once mounted?

Thx
Jon

Posted by joninnj on 05/02/08 - 4:26 AM

Posted by Pete on 05/02/08 - 5:34 AM

Hello, I did drill the plate and mount it to the transom and the engine to the plate.
I did not get much perf gain for the effort. One benefit of rasing the engine was not needing the Doel fins any longer. The big issue was weight moved back 4".
I have a 27 gallon fuel tank under the rps and the battery and oiler in the console. I also have a kicker on the transom of about 90 lbs. My boat now took much water on to the deck when in reverse and worse when launching in less than perfect conditions and terrible in a following sea.
With the plate off and the engine mounted in the 3rd hole from the top I have the same perf gain (if you want to call it that), no doel fin needed with engine at this height, better hole shot and quicker plane. I had no complaint about hole shot or plane before.............. Without the plate I dont have the issue of water over the transom. Seems to be a delicate balance.
I had no issues raising the engine on the plate. I raised it as much as 3" from its original position.
Pete

Edited by Pete on 05/02/08 - 5:43 AM