Shetland 570 Engine

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garaldo

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I've just bought a Mercury 75hp four stroke (2004-2006 ish) for use on my Shetland 570. The boat was rated up to 115hp when built in the early 80's, but I am concerned about the additional weight of the new engine (it replaces a Mercury 80hp 2 stroke). Any idea of the weight of the new engine, and any comments regarding suitability would be appreciated.
 
Welcome to the forum.

I cant remember the exact weights, but the 2 stroke mercury 80hp would have weighed about 120kg and the max size 115hp about 140kg.

A modern 4 stroke 75hp weighs about 160kg.

If your transom is sound then I dont think the extra weight will be a problem, but any weakness could be exposed and it might end in tears.
 
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If you're worried, why not make up a metal plate to go either side of the transom, and glass that to the transom with a reinforcing brace bar or something. I'm just thinking of trying to spread the load out over a wider area of transom.

I'd also speak to Shetland, they'll have a good idea - but I think people often "over engined" shetlands, so I'm guessing (normal disclaimers apply) you'll be ok.
 
Had a 90 hk tower of power Merc 6-cyl on one of these with no issues whatsoever. Even had a 5 hp kicker besides it.

If it is sound it will take your 75 easily.
 
The 570's Hull was aparently used in Racing!?

Mine wasn't, as I bought it with a 20hp Mercury...:p

The weight won't be an issue, compared to the thrust issues of a far more powerful engine. You can easily relocate the fuel storage to the Port side seat/locker to trim the weight forward a bit. It will also compensate for you helming on the other side...
 
landlockedpirate said:
Welcome to the forum.

I cant remember the exact weights, but the 2 stroke mercury 80hp would have weighed about 120kg and the max size 115hp about 140kg.

A modern 4 stroke 75hp weighs about 160kg.

If your transom is sound then I dont think the extra weight will be a problem, but any weakness could be exposed and it might end in tears.
Click to expand...

Yup. The mercury tower of power (which included a 115hp) weighed 136kg and as you say the 4 stroke now being proposed isn't that much heavier.

The engine weight wont break the transom at sea even if you put a 350hp Yam on the Shetland. The biggest engine loads on a transom occur when you hit a road bump or pothole on the trailer

Incidentally, OT, the nice new yamaha 70 4 stroke weighs only 110kg or so
 
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