outboard upgrade

[Gibsonman2005]

I have a 1959 dorsett Catalina 17'. I'm thinking of putting a mid 80's 90hp Mercury 2-stroke on it (got a cheap one on Craigslist). It weighs about 300lbs. My old 40hp weighs about 200lbs. 20" of transom on my boat...is this a good idea? I've seen 1 pic of a 60's dorsett catalina with this same motor on it...but that's just the thing...only 1. Did all the others sink? Just curious what you guys would think of this swap out. Thanks in advance.

 

[Fleetwin]

Well, your old 40 HP was probably 35 HP, at the prop-at best. You are now contemplating almost tripling that HP. Probably doubling the weight too.

I think you would be-pushing it! No pun intended.

 

[Woodonglass]

I think you'll be fine. Your boat is rated for 80 hp. The 90 will be a bit BEEFY but there's no law that says you have to run her WOT!!!! The weight shouldn't be an issue either other than you'll lose some passenger capacity. It should be noted that in some cases if you Over HP a boat some Insurance companies will NOT pay claims.

 

[Gibsonman2005]

Sooooo, in my infinite "wisdom" I looked for a diff motor that weighs less...maybe 25lbs less...I dunno if it even matters at these weights, I also picked up (today) a Johnson 85 hp v4. I know what you're thinking, but dude who do you know that can find two big badass motors that run for less than $600?
Anyway, as much as I love the sound of that merc I like the lighter motor. Model #J85MLCS
ANY experiences with these motors will fall on wanting eyes and ears. Thanks.

 

[Woodonglass]

I recently restored a 1976 85hp Johnson and LOVE it! Put it on my 15ft runabout and she FLIES!!!!

 

[Watermann]

If your Catalina looks like the pic I found then I wouldn't be concerned at all about a 90 HP being on her. Unless she hasn't been rebuilt and is rotten inside.

 

[Gibsonman2005]

Forum wasn't working for me at all this weekend...wouldn't load properly and/or wouldn't load at all...
Anyway, I've seen pics of that particular boat and driver before! On google images... I think he's running a couple of older johnsons but I don't know what model they are.
I've been working on my boat on weekends since March rebuilding my boat. Stringers, transom, deck, painted all the interior so far. Outside will be next. Then it's mount the motor and do the final touches.

Question: I'm thinking of getting a stainless plate (1/8" x 24" x 24" or so). I want to put it between the motor and the fiberglass. I've got to drill holes through the transom so I'm thinking it might help disperse some of the pressure on the fiberglass when I tighten it up. Maybe even do both sides of the transom that way. Thoughts?

 

[TruckDrivingFool]

Not saying you can't do it but it shouldn't be a concern on a properly rebuilt transom.

 

[Watermann]

If you want a motor pad rather than mounting it with more holes into the transom. just drill the 1/2" bolt holes that are there for the motor through the new pad, back butter the pad with 5200 run the bolts through and snug them down. Once cured remove the bolts and install the motor.

 

[Gibsonman2005]

So, just a simple rubber pad? Like one of those 30-40$ jobs? I had never heard of or seen one until now...just found a love for boats and boating a year ago...
So how about the top edge of the transom tho?

 

[jigngrub]

These are the proper motor mounting accessories for a professional outboard motor installation:
http://www.iboats.com/T-H-Marine-Tr...89287933--session_id.371403889--view_id.40150
http://www.iboats.com/Transom-Suppo...287933--session_id.371403889--view_id.1185373

The two different sizes are for the top and bottom set of holes. They distribute the compression pressure of the bolts and lateral forces of operating the engine, and you won't look like an amateur with just "big washers" holding your motor to your transom.

 

[Gibsonman2005]

Do these mount onthe inside surface of the transom?

These are the proper motor mounting accessories for a professional outboard motor installation:
http://www.iboats.com/T-H-Marine-Tr...89287933--**********.371403889--view_id.40150
http://www.iboats.com/Transom-Suppo...287933--**********.371403889--view_id.1185373

The two different sizes are for the top and bottom set of holes. They distribute the compression pressure of the bolts and lateral forces of operating the engine, and you won't look like an amateur with just "big washers" holding your motor to your transom.

 

[jbcurt00]

Yes, sort of large oversized washers, backing plates