New member here. No boat yet, but very interested in purchasing a NS30.
I’m looking at one that’s in great condition, but somewhere along the line was repowered with a Westerbeke 38B4 (4 cylinder, 38 hp, with V-drive). This appears to be much larger than the original (3 cylinder, 27hp, from what I can find on the web) which is concerning to me due to low load (wet stacking and glazing), extra weight, extra stresses on prop shaft and bearings, etc.
Any opinions about how concerned I should be about this? Is this a common upgrade?
38 hp is to much for a N30 whether it’s shaft drive or saildrive. I was going to install a Beta 35 because it is a four cylinder with lower RPM. Beta convinced me a 30hp was a better choice and they were right. Beta has converted the Kabota into my opinion one of best small marine diesels. There replacement parts are priced right and if possible they will give you a NAPA part number.
Michael
Homeagain
NU30 219
1 Like
Ward.Woodruff
(Ward Woodruff N33 #8 Margery Niantic Bay, CT)
3
what year is the Westerbeke
Ward.Woodruff
(Ward Woodruff N33 #8 Margery Niantic Bay, CT)
4
How many hours? Does it run Okay? Does the prop load up the motor under cruise RPM? If it runs okay and has been in the boat for years, I would not worry about the size.
I haven’t got to the sea trial yet, so I dont know how well it loads up, but the owner told me by phone that he cruises it around 2000 rpm. Not sure of age, but it has about 1800 hours.
One consideration is that this engine is rated as 37hp @ 3600 rpm. A diesel engine should be regularly run at about 75%-80% of full rpm, so for this engine that’s about 2700-2900 rpm. If the engine has only been cruising at 2000 rpm, it may have internal problems and wear not readily visible. Maybe you should consult a diesel mechanic first.
Low Load. It does seem overpowered. Running a diesel engine at lower power will shorten its lifespan, but not as much as other things such as running it for only short times (in/out of marinas) and not getting a good warmup. A well maintained and properly specified diesel should last for 8K hours. A well maintained and over powered diesel might “only” last for 6K hours or more. How many people actually get anywhere close to 6K hours on their engines? If you ever have to replace this engine you might want to spec it a little better, but I don’t think I’d worry too much about running it under low load. Just be sure you run it long enough to warm it up when you go out, and keep up with your maintenance so something else doesn’t come along and bite you before the thing wears out.
Weight. The previous W27 is listed as 434 pounds by Westerbeke. Your current 38B4 is listed as 419 pounds by them. So your newer, more powerful engine is actually 15 pounds lighter, though I don’t know how the rest of the drivetrain compares.
Extra stresses. Generally, a drivetrain is specified as a system from the engine to the propeller and the length and displacement of the boat is factored in along with that. If that was done with this engine replacement, then there should not be extra stresses to worry about. If the engine was replaced onto the existing drivetrain I think I would be concerned.
If you haven’t done the test sail yet, be sure and run the full throttle test. Ideally you should hit around your hull speed at 3600 RPM (spec for your engine) at WOT (wide open throttle). Be careful that you don’t over-rev it with all that extra power. If you are getting a mechanical survey, the mechanic should come along with you on the test sail. They’ve come with me on all the test sails I’ve had done. (3) Also, have the mechanic test the oil as part of the survey. That can tell you a lot about how the engine has been running. Then listen to the opinion of the mechanic pertaining to that particular engine.
I would try to figure out the circumstances that led led to installing an engine that appears to be mismatched.
Two thoughts….
I see plenty of well loved NS30’s that sell for fair prices. If this boat isn’t an exceptional deal or there isn’t a reasonable explanation for the odd engine choice I’d pass.
I wouldn’t give this boat “extra credit” for the engine even if it is relatively new, this goes back to the price.
I agree, though it might be impossible to do. It could be something completely legitimate like they frequently had a long slog home against a strong river or tidal current and prevailing headwinds. There are a lot of those situations in the PNW, though I have no idea where this boat is from - or where it will be used.
Sorry this one didn’t work out. Let us know where you are and what you are looking for…. you never know when a well loved boat might be looking for a new steward.
Don’t know where you’re located, but there are at least eight Nonsuch 30s and 33s listed on the INA Marketplace that were posted recently enough to very likely still be on the market.
And N26s and N36s aren’t bad, either. There’s a bunch out there, too.
In my opinion having a larger diesel is fine as long as you have a properly sized prop so you can cruise at optimal RPM, which from I have read is 70-80% of 3600 for the Westerbeke 38b4 So aim for 2500-2700 rpm for cruising and then you can calculate the optimal prop pitch which would have smaller pitch than lower 30hp d’s. To do this you need to know the gearbox ratio, estimate slip , etc. A sea trial would also give you a good idea 2500 rpm and do ~6.5 knots
I’m not sure how much stock to place in ChatGPT, but it implies that the W38-four was actually offered as a factory option for 30’s built in the 90’s. Can anyone confirm this?