X2.... Since most manufacturers build in a certain load above the rated safe load, and if money wasn't all that important, I'd tend to do the same thing. Understand this is NOT a recommendation, just sayin what I would probably do.
Much like me running a 18hp Kicker on an EZ-IN kicker bracket for several years even thought the bracket was only rated for 10hp. But then again, I've never considered myself as the brightest candle in the box... so what the heck do I know.... :head:

More to look at.
http://www.wholesalemarine.com/th-ma...extension.html

I think you are going to have trouble if you mix metals unless you can insulate that aluminum plate from the stainless angle, the plate will act like a sacrificial anode to the bracket, especially in saltwater.

he has no need for an aluminum plate.... all he needs is angle and bolts

i think he was going to put some plate on the inside of the transom for backing plate

Buy this hull get a free jack plate, $300. Then flip the hull.

http://augusta.craigslist.org/boa/4694174420.html

Not precisely. I asked how it should be built, and someone suggested to put a plate on the inside.

It's clear from this thread everything should be aluminum, and consensus appears that it isn't strictly needed. The force applied is greatest at the inside top bolts of the transom and the outside bottom bolts due to the whole thing essentially being a lever. The bolts are stainless only because aluminum bols aren't strong enough (if they even exist).

I personally am uncomfortable using angle for an engine this size, I would feel better if it were at least "c" channel. That is just my gut feel, no actual numbers to back that up. But I have looked at pictures of Z-Lock for comparison. Most notably, the hi jacker design (which resembles the angle design) is rated up to 150hp. For larger engines, the design changes. The amount of force needed to move 2000lbs of boat, plus 1000lbs of fuel, people, and gear has to be significant ... Plus it must apply some amount of torque due to the prop.

[EDIT] Just found this design that uses angle brackets here:
Machine Shop Goes up to 300hp, so maybe angle is OK. I am stopping by a metal place Friday to see what is available and what it costs.

You know.... at $143 shipped THIS^ is another good option

If not you could use this design for yours..... only downside is a couple more holes n the transom.

I understand the sentiment, but I am an (electronics) engineer working in the nuclear power industry. My design comfort level starts in the 30% to 50% margin range, and if I can talk people into a more robust solution, I will. Then I add a backup system. Actually, we like four backup systems for anything really critical.

It may work just fine for a long time. I understand perfectly well that T&H designed in margin, but I could never sleep well at night using something beyond rated capacity. Fukushima got hit by almost 10x worse than it was designed for, which has no bearing on this topic, but it does reinforce the idea that safety can never have enough margin.

While I appreciate the viewpoint, I'd never be comfortable with it

I'd use a 1" plate of aluminum! You know, to give myself some margin ... good idea, I'll price that out Friday, too.