I’m new to this group and have a question to run by other Nonsuch owners. I have a 26 ft Nonsuch that had a 20 HP Westerbeck engine that died this spring. The boatyard finally put in a 21HP Yanmar engine and states that everything else is the same ie the shaft rudder and right turning prop. Since the new engine, the boat pulls heavily to starboard when motoring at about 2500 rpm. It did not do this with the old engine.
I wondered whether anyone has any thoughts as to how to remedy this situation. thanks so much.
Cynthia owner of Sal out of South Portland Maine.
I’ve driven many boats over the years with a similar problem but never a Nonsuch. However, I don’t understand why yours is doing this with the same prop. Is the prop now closer or further from the rudder then before? Are you still turning the same RPM for the same speed??
Joe Valinoti
S/V IL Gatto NS30U #221
Sea Harbour YC
Oriental, NC USA
PS – Note how most of us sign off
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This doesn’t sound like an engine issue. Was any other work done when the boat was at the yard?
Paul M
NS30U #211 Sandpiper
Cowichan Bay B.C.
No just replacing the engine and new shaft as the old one was pitted. That's what they say.
Cynthia owner of SAL out of Portland Maine.
thanks
Cynthia Sortwell, MD
30 Danforth St
Portland, ME 04101
207-879-2556
I believe the Westerbeke 21 and 18 was clockwise RH rotation on the N26 same as the 13. The spec sheet for the non sail drive Yanmar also says clockwise rotation of the shaft. If it’s the same prop or even a new RH (clockwise looking from stern) prop I don’t know why it would now pull heavily to starboard when it didn’t before.
What about in reverse? Does it behave differently now than before. Is there prop walk to port in reverse?
The 26 should have very little pulling in any direction and very little prop walk with the RH prop. But if you were to install a motor with LH prop it would have a great deal of pull to starboard when motoring forward. It’s because the shaft is angled down and to starboard.
Tom
26C #28
Penetang
Tom: I think Cynthia said it was the same prop. Which, as you know, can’t be used in the other direction. Quite puzzling!
Joe Valinoti
S/V IL Gatto NS30U #221
Sea Harbour YC
Oriental, NC USA
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So this is what I found out from the boat yard.
Both engines are right-hand rotation.
Old engine was a Westerbeke W21 with 21 hp @ 3000RPMs, it had a HBW50 gear with a 2:1 ratio
New engine is a Yanmar 3YM20 with 20 hp @ 3600RPMs and a Kanzaki gear with 2.62 ratio.
Westerbeke shaft speed at WOT was 1500 RPMs and with the Yanmar it would be 1374 RPMs.
We used old prop on new engine install and hit 3695RPMs at WOT.
The boat yard told me that they put everything back in the same way so I’m assuming the prop is same distance from rudder. (I should have taken pictures)
The one sea trial where I backed it up it seemed the same. It’s just underway at 2500 rpm the pull is quite strong.
Cynthia owner of Sal from South Portland
Thanks
Cynthia Sortwell, MD
30 Danforth St
Portland, ME 04101
207-879-2556
Clinical Associate Professor of Psychiatry
Tufts School of Medicine and
Maine Medical CenterThe Westerbeke 21 and the Yanmar are similar in length but my guess would be that the prop on the current setup is closer then before thus increasing the effect of prop wash over the rudder.
Mark Powers
La Reina 26C
Vancouver, B. C.
I don’t know about distance between rudder and prop, but my 26 also wants to turn to starboard under power. At 2200 rpm, the effect is like a puppy on a leash who wants to sniff a flower. At 2500 rpm, it’s more like a big dog who’s a gonna chase that squirrel. The argument lasts longer and requires a much firmer grip.
I have the original Westerbeke 21, so I suspect something other than the engine manufacturer is at play here. Wish I knew what, although it’s more an object of curiousity than a significant problem for me.
Not sure if you’re new to the boat, or just to the group, but congrats either way, Dr. Sortwell.
– Bob
Solar Wind, Nonsuch 26C, #143
Last weekend I made a test. With the wheel brake completely off, motoring at the usual 2300 rpm, flat water, going in a straight line. Letting go the wheel it will turn to starboard, eventually the boat will go in circles.
Holding it straight with no wheel brake requires a light grip.
Probably why I always have a bit of the wheel brake on so I can let go for a while and not change course. I never noticed this before.
Tom
26C 28 Westerbeke 13
North Star
Penetang
Thanks for all the replies about my 26 nonsuch pulling to the starboard after new motor. It’s been very informative. I’m wondering whether that is common to all 26 nonsuches? It is so weird that it wasn’t like that and now is.
Cynthia
Sal out of Portland maine.
Cynthia Sortwell, MD
30 Danforth St
Portland, ME 04101
207-879-2556
Clinical Associate Professor of Psychiatry
Tufts School of Medicine and
Maine Medical Center
Hi All, I have read the posts about NS26 pulling to starboard with interest. My guess is that the offset to starboard of the shaft will force the hull to pivot around an axis somewhere along the keel. It should not happen with a properly aligned sail-drive.
Jorgen Moller
Pondus NS26C, #33
RCYC, Toronto
In July, purchased and launched a N26. It has a Westerbeke 13.5 with a folding 2 blade Gori prop. No issues with pulling to starboard when operating with power.
Howard
Stray Cat N18
I think the weather helm under motoring varies as a function of engine, transmission ratio, prop diameter, prop pitch, number of blades and engine off set. So each change in these variables will have a impact.
Assuming you motor at 80% of you engine RMP… well there are 5 variables that change prop walk so each boat will be different. I had for a brief time a 3 blade 14/11 fixed prop. It was spec to the engine / transmission and at 80% or 2400 rpm the boat made 5.1K in flat water… with my Gori 2 blade 15/11 I get 5.5K and better thrust in strong winds / current… Prop walk is such that you would not motor without a hand on the wheel.