Repower of Nova Trawler

I am wanting to try to get more speed out of my 1983 Nova 42 Sundeck. Is the semi displacement haul of this boat capable of more speed if it is repowered? Can this boat be repowered with current stringers which are filled with foam? Has anyone had experience with particular scenario?

Personally I would look at selling this boat and buying a boat that is faster. Repowering with larger engines will literally cost a fortune and you will never recover those costs. You could easily spend $100K on the repower.

Comodave said:

Personally I would look at selling this boat and buying a boat that is faster. Repowering with larger engines will literally cost a fortune and you will never recover those costs. You could easily spend $100K on the repower.

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This is very good advice.

Years ago I had my own small boat yard. I had a gas powered Uniflite 42 that I desperately wanted to repower with 400 hp diesels. The boat was originally designed for such horse power. All I had to do was drop in new engines and transmissions. I ran the numbers every which way. Even with all my labor being no cost I couldn’t make it cheaper than selling the boat and buying another boat with the big engines.

If yours is anything like mine, you will need to triple or quadruple the hp to get much more speed. My SD hull does 8 knots economically, is capable of 10,ish, at WOT, but burns more than 2x the fuel to do so. To achieve any more, you need to be able to get "over the hump" onto a plane. Since to do so means moving 20 tons, a few more hp won't get you there. Then you would be looking at reinforcing the stringers, changing out all of the systems, water in, exhaust, helm controls, etc all of which is $$, so quickly into 6 figures. You may not even find a high hp pair to fit your available space.

8-9 knots is what SD trawlers do. It`s the brick like design of the hull. A power increase will yield a small increase in speed and an eye watering consumption of fuel. A higher power engine swap is not a solution.

I appreciate the replies. Looks like a repower is a no go.

At first blush a repower looks doable. Then you get into the details. You never realize all the little things that go along with a repower.

The props, shafts, exhaust and motor mounts are the obvious changes. Once you get going you start running into all kinds of unforeseen issues. Thru hulls often need replacing and relocation, fuel lines often need changing, controls, electrical the list just goes on of items that you just never think about.

I hear you on that. I love the boat , but just wish she would go a little faster. She has two perkins engines. Perkins was bought by caterpillar and they are starting to discontinue parts. Another
Reason why I thought about it.

Comodave said:

Personally I would look at selling this boat and buying a boat that is faster. Repowering with larger engines will literally cost a fortune and you will never recover those costs. You could easily spend $100K on the repower.

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Sound advice.

After thinKing about it I realized that my estimate of $100K was probably low. A couple of larger diesels could cost $80K just for the engines. Then there is the installation. The work involved is almost incredible and goes on and on. Everything involved with the engines would change. Maybe even work on the stringers. Motor mounts, gauges, wiring, shaft, cutlasses, props, exhaust, etc. All of which will be custom work at $100+ per hour. Look at sbmar.com for some videos of engine repowers and you can see some of the work involved. And those guys are really good and very experienced at it. Maybe you get a yard that has never done one or maybe you get a good experienced yard. But if you get a yard that doesn’t know what they are doing and are learning on your dime it could be horrible. IMO time for a new boat. I am very experienced at that since we are on our 24th boat in 53 years of marriage…

I even penciled it out with used engines but the list of little things just kept adding up. Not to mention your boat is out of commission for a whole season. That’s a lot of insurance and moorage fees added to the cost of a boat you can’t use till the job is done.

Direct replacement is soooooooo much easier.