Boat has never had transom drilled before. Where do I start?

[JohnnyMat]

I have an 1987 Starcraft SS160 with a 1983 Johnson 70 J70ELCTE (20"). Transom height is 20-1/2" from bottom of keel to the top of the transom.

The transom on this boat has never been drilled because it had a 1976 Evinrude 35HP with the hand tightened transom mounts. The transom is absolutely pristine with no holes for a reference point! Needless to say, I don't want to just start drilling into this thing. I want it done right the 1st time.

So here is where I am at currently at. I have found the center of the transom, I hung the outboard directly onto the transom, traced the transom bracket holes onto the transom skin and was ready to begin drilling.

I then read/watched a few posts/vids about setting the proper height...and then the confusion kicked in!

Do I just drill the upper most holes and then adjust the height from there? From what I can tell, I will end up needing to raise the bracket to the 2 or 3rd hole in order to get the cavitation plate above the lowest part of the keel.

Also, do you guys recommend putting some type a material between the transom bracket and the transom skin? Polyethylene/PVC board, Aluminum plate, Wood (not pressure treated), etc...?

I hope this all makes sense. Any help would be appreciated. I can't find much info on drilling and mounting an outboard on a brand new aluminum boat transom (like mine) using an 80's outboard.

 

[oldboat1]

Construct a template out of 1/8 - 1/4" plywood.

 

[JohnnyMat]

Construct a template out of 1/8 - 1/4" plywood.

What am I making a template of exactly...the outline of the transom bracket? I do have that traced directly onto the transom skin when it was hanging on top of the transom. That would be it's lowest possible point.

 

[oldboat1]

template would be of the motor transom bracket. Check against the one you already did on the transom. Clamp to the transom with a c-clamp, and do measurements for anti ventilation plate height -- usually even with the boat bottom. If you think you are going to experiment with mounting height, get an adjustable mounting plate -- jack plate -- and drill/mount that.

 

[racerone]

Put motor in the center of the boat.----Use large C-clamps to pull motor to the transom.----Drill the top hole at the top.----Drill near top of the slot on the bottom..----Done.

 

[JohnnyMat]

Put motor in the center of the boat.----Use large C-clamps to pull motor to the transom.----Drill the top hole at the top.----Drill near top of the slot on the bottom..----Done.

Okay, that's what I was looking for. The starting point.
I wasn't sure if I should hang the outboard directly on the transom and drill the holes at that spot -OR- raise the unit up a little and drill the holes a bit higher, since the outboard will need to be raised anyway.
The way it looks hanging directly on the transom, I will need to use the 3rd bolt hole to get that ventilation plate even with the bottom of the boat.

I appreciate the input.

 

[JohnnyMat]

Put motor in the center of the boat.----Use large C-clamps to pull motor to the transom.----Drill the top hole at the top.----Drill near top of the slot on the bottom..----Done.

Got the holes drilled and everything lines up. Do you recommend putting any material between the outboard transom bracket and the outside of the transom? I've neen people using wood, plastic, or aluminum plates. I assume its to reduce wear on the transom skin.