Thread subject: Whaler Central - Boston Whaler Boat Information and Photos :: engine mounting holes

Posted by Binkie on 11/16/14 - 9:23 AM
#1

I'm planning on re drilling the engine bottom mounting holes on my 15'Whaler today. Tho old bottom holes, I plugged and glassed over. The top holes are already drilled 1" centers below the top of the transom. I didn't plug them as I figured redrilling them 1 7/8" as shown in the diagram might just weaken the structure of the hole.
Here is the diagram;
http://www.whalercentral.com/articles...icle_id=82

I laid out the bottom holes using the green hole dimention as shown on diagram (6 1/2". This layout would put the bottom hole above the splashwell. Now before I drill; I should check the engine bracket just to be sure it will work. The engine (1999 Yamaha C60 2 stroke) is mounted on an engine stand, and I find the green holes won't work even if I mount the motor 2 holes up. I am planning on mounting it one hole up as the top holes are allready drilled 7/8" too high anyway. Even using the yellow hole (7 1/4") It will only work mounting the engine 2 holes up, which as I mentioned before will be mtoo high as the top holes are only drilled at 1" instead of 1 7/8".
Does this diagram not work on a fifteen foot whaler? I'd rather not drill holes 8'' and use lags in the bottom holes.

Maybe I need a bracket.

Posted by Binkie on 11/16/14 - 9:27 AM
#2

Sorry, typo , I laid ot the top holes at 6 1/2" not seven.

Posted by wlagarde on 11/16/14 - 12:03 PM
#3

Binkie - It will work - drilled 2 holes up - the lower bolt holes will just clear the splash well by about 1-1.5". You may need to angle the lower holes slightly upward rather than drilling them exactly perpendicular to the transom to be sure they clear the splash well. I did my 1976 Sport 15 last winter. Here is my project page: http://www.whalercentral.com/userphot...lbum_id=64

Edited by wlagarde on 11/16/14 - 12:03 PM

Posted by roymiz on 11/16/14 - 4:26 PM
#4

Just remember to match the angle of the transom...if you drill straight in, you'll definitely get too close to splashwell...

Posted by tmann45 on 11/16/14 - 8:57 PM
#5

Binkie wrote:
I'm planning on re drilling the engine bottom mounting holes on my 15'Whaler today. Tho old bottom holes, I plugged and glassed over. The top holes are already drilled 1" centers below the top of the transom. I didn't plug them as I figured redrilling them 1 7/8" as shown in the diagram might just weaken the structure of the hole.
Here is the diagram;
http://www.whalercentral.com/articles...icle_id=82

I laid out the bottom holes using the green hole dimention as shown on diagram (6 1/2". This layout would put the bottom hole above the splashwell. Now before I drill; I should check the engine bracket just to be sure it will work. The engine (1999 Yamaha C60 2 stroke) is mounted on an engine stand, and I find the green holes won't work even if I mount the motor 2 holes up. I am planning on mounting it one hole up as the top holes are allready drilled 7/8" too high anyway. Even using the yellow hole (7 1/4") It will only work mounting the engine 2 holes up, which as I mentioned before will be mtoo high as the top holes are only drilled at 1" instead of 1 7/8".
Does this diagram not work on a fifteen foot whaler? I'd rather not drill holes 8'' and use lags in the bottom holes.

Maybe I need a bracket.


Binks, measureing the bottom holes distance from the top holes will be like drilling them one color higher on the transom than shown in the diagram.

So, drilling the red holes (8" below top holes) would place them at the same height (+1/8" higher) in the transom as drilling the yellow holes since your top holes are 7/8" to high to start with.

Thinking from the top of the transom: normal holes are (according to the diagram):
Top holes - 1 7/8" from top of transom
Red (normal) holes - 9 7/8" from top of transom
Yellow holes - 9 1/8" from top of transom
Green holes - 8 3/8" from top of transom

Now since your top holes are drilled 7/8" higher than normal, the bottom holes will be:
Top holes - 1" from top of transom
Red (normal) holes - 9" from top of transom
Yellow holes - 8 1/4" from top of transom
Green holes - 7 1/2" from top of transom

Summary: drilling the holes as measured from the top holes (assuming mounting engine in lowest possible position due to bolt placement):
Red will be equivilant to 1-hole up (bolt in top bracket hole, all the way down)
Yellow will be equivilant to 2-holes up (bolt in next bracket hole, 1-hole up)
Green will be equivilant to 3-holes up (bolt in next bracket hole, 2-holes up)

If I have confused the issue, send me a PM or email.

Posted by Binkie on 11/17/14 - 12:02 PM
#6

Thanks for your help. I drilled the red holes which places the engine one hole up. Its the lowest position I could go and I drilled the holes with an upward slant which gave me about a 3/4" clearance from the splash well.

Posted by tmann45 on 11/17/14 - 12:35 PM
#7

Good to hear that it worked for you .