transom power rating

[Mykul]

Hello, I am new here and fairly new to boats and I have a few questions. I have a 14' 1963 Eatons Viking it is rated for a 65hp out board (which is rated at the flywheel).
1. What do I have to do to safely put on a brand new 60hp (@the prop shaft) out board?
2. What all contributes to the power rating of the transom? Is it the strength of the transom and how it’s connected to the boat or dose the shape and design of the entire boat play a role in how much power a transom can handle?
3. The words “transom bracket” have been used on this site, what is it? And would it help with my situation?

[marshmat]

Welcome aboard the forum, Mykul.
Power ratings are determined based on a number of criteria. The big one is the net volume of the hull, measured to the static float plane (the deepest immersion it can handle without filling up with water). The shape of the bottom (flat, or amount of V) is a factor; so is the presence/absence of a motor well and the shape of the baffles around such a motor well. The beam at the transom is considered along with the boat's ability to support the weight of the engine while maintaining proper trim. The operator position and control type are considered, along with a few other factors. Finally, the transom is (or, rather, should be) engineered and constructed to handle the maximum loads the biggest expected engine will apply, with a substantial margin of safety and considerations for fatigue, vibration and impact.
A transom bracket is simply a bracket, bolted to the transom, that sets the outboard engine back anywhere from a few inches to a foot or more behind the transom. This allows you to raise the engine height a bit, reducing parasitic drag, but it also increases the moment arm caused by the outboard's weight- which can cause trim problems.
Before mounting a new engine, you need to first confirm that the boat can handle the weight of the motor at the transom without trim problems. A 2007 60hp is a fair chunk heavier than a 1963 60hp. You'll also have to take a really good look at the structure of the transom and its knees/braces, making sure they're in good condition with no fatigue, rot, cracks, etc.

[Mykul]

Thank you, But obviously what I was thinking of wasn’t a transom bracket. A transom bracket is kind of like a jack plate right? What’s the part of the boat called that connects the transom to the floor in the center of the boat parallel to the sides? Is that what you referred to knees/ braces?

[USCGRET/E8]

(Quote) A 2007 60hp is a fair chunk heavier than a 1963 60hp.

I disagree...a 2007 60hp is a nice little lightweight 2 cylinder.
A 1963 65hp is a big ole V-4 engine.
I would be comfortable with that new engine on that old boat, if the boat is solid.

[marshmat]

Most of the new engines on the lakes I frequent are substantially heavier than their older cousins...thanks mainly to more robust construction and a great deal more sophisticated equipment. 60 hp units are usually 3-cyl inlines today (the 107kg/240lb Evinrude Etec 60, inline-twin two-stroke at 863 cc, is about as small and light as 60s come- and it shares that block with the 40/50, so it's really pushing the limits. The Merc 60 is a 4-cyl inline four-stroke,995 cc and 112kg/248lb.) But I digress.
Knees and/or braces are terms used to describe the structural members that connect the transom to the hull and stringers.
I agree with USCGRET that provided the boat is solid and in good shape, the new engine is probably safe and useable.

[Mykul]

How do I gadge how solid the boat is? I have looked again and I have seen no cracks or stress marks in the fiberglass. it feels solid but how can I be 110% sure?

[marshmat]

If you can post a few photos (800x600 px or better, and with clear focus and even lighting) there are folks on here who can help to point out the probable trouble spots and might be able to spot signs of fatigue.

[Mykul]

How many pics do you need to find fatigue? What dose fiberglass do when it is fatigued? Dose it turn white like when you bend a piece of plastic, dose it just crack, or dose it get soft spots? My next step in looking for stress is with a magnifying glass. And I would rather not spend hours uploading several dozen high quality pics as my conection is not the fastest.

but if I need a magnifying glass am I being too paranoid about streangth?

[USCGRET/E8]

There would be several large stress cracks near where the motor mounts. The boat probably has small minor stress cracks all over, no problem. To check the wood inside the transom, drill some holes on the inside, but don't go all the way through. A 3/4" hole saw (made for installing the latch barrel on doors) removes a good plug to inspect the wood and you can glue it back in if the wood is good. If the wood looks good and is not wet, only 2 or 3 plugs should be enough. I'm shooting in the dark here a bit, as I don't know the style of the boat and such.

[Mykul]

As I said before threre are no *0* cracks in the fiber glass on or neer the transom, not even in the gelcoat. As for the plywood it was replaced just before I bought the boat, so it is brand new. The transom is curved, would that prevent cracks around the motor mounts?