Submerged. There were two of us in the cockpit.400 pounds between the two of us I am guessing
this spring I installed a new shaft and had the propeller faired. Is this t.ypical or maybe weight distribution is off. Any input is gratefully appreciated
I apologize for any typos here dealing with a new format that on my IPad does not show everything typed.
Steve O’Malley
N26C 171 ANU
Marblehead MA
I have no idea what’s causing this, Steve.
But, based on experience with mine, I feel pretty confident saying that neither the weight in the cockpit nor the RPM are sufficient to be the cause of an N26’s stern digging in to that extent.
I find myself wondering (apologies if you’ve already considered these factors):
I wish I had some advice to offer. I’ll be very interested to hear what more knowledgeable folks have to say on this topic.
– Bob
Solar Wind
Nonsuch 26C, #143
The stern digging in at 1800 rpm is unusual. The stern of my 26 will dig in only above 6 or 7 knots, which would be about 3000 rpm. There would be about 280 pounds of people in the cockpit and I have an 18HP engine.
If you passenger is not onboard does it still happen?
John Barbour
2U Nature
Toronto
Bob and John,
Thank you so much for your response and input. I will re check and confirm the rpm and speed and report back. My water tanks are empty so maybe lacking weight forward. Nothing of any significant weight in the cockpit lockers. I will also get some photos. Thanks again.
Cheers
Steve O
N26 171. ANU
In calm water in my boat, 900-1000 rpm yields about 2 kts, 1800 gets maybe a bit over 4 kt, 2800 rpm pushes about 5.75 kts, 3000-3100 gets about 6.3 kts. Like John, I don’t see signs of squatting 'til approaching 6.0 kts.
I’d be curious what your rpm/speed profile looks like. I’d also be curious what happens if you watch the stern of your boat at the dock, have people get into the cockpit one at a time, and see how much it goes down with each additional passenger.
– Bob
Solar Wind
Nonsuch 26C #143
Steve, you are lucky to be in salt water. The exhaust would be lower in fresh water. You can improve the situation by using your water tanks up forade to trim ANU and not fill the fuel tank more than necessary. When I had the wishbone rig, my heavy Universal 16 diesel would fully immerse the exhaust by about 5 knots. It did not seem an issue other than creating the “famous” (?) Nonsuch moustash on the transom. Using a higher 45 cetane fuel makes for a happier and smoother engine and cleaner exhaust. Standard diesel is about 40 cetane.
John Newell,
Mascouche 26C 1
Toronto
Hmm. This led me to do a quick search on the web.
As near as I can tell from trying to research regulations (never an assured answer), California requires a minimum cetane level of 47 for diesel sold here. Chevron seems to be the company with the most, and largest, fines for selling sub-standard diesel in my state.
– Bob
Solar Wind
Nonsuch 26C #143
I never really thought about this issue or even bothered to check, but was out last night, calm water, four people in the cockpit, empty water tanks, 2400 rpm (Westerbeke 21 hp engine) and about max speed and noticed my boat was doing the same thing.
Mark
Penguin
Nonsuch 26C. #174
Washington Island, WI
I’m not sure, but this post photo may be in violation of our discussion group “Standards” rules under the subtitle ”Definition of Pornography
Joe Valinoti
S/V IL Gatto NS30U #221
Sea Harbour YC
Oriental, NC USA
~ ~ ~ ~ ~ (_ ~ (_ ~ (_ ~ ~ ~ ~ ~ ~ (_ ~ (_ ~ (_~ ~ ~ ~
Only two things can cause the stern to go down. One is the weight and the other is the height of the water under it. If the weights don’t move then the stern went down because the water was lower.
As any displacement hull approaches hull speed its quarter wave approaches the stern and as speed increases the stern starts to drop into the trough between the bow wave and the quarter wave. At the same time the bow starts trying to climb up the bow wave.
That’s why fuel consumption goes up dramatically beyond hull speed. You are literally powering up hill.
Paul M
NS30U #211, Sandpiper
Cowichan Bay, B.C.
Last time I was out, I checked the exhaust’s water clearance. At 2,000 rpm and 4 knots, the exhaust was an inch above the water. At 5 knots it was clear still. Prior to the modifications I made, the exhaust would submerge in the 4 knot region in “fresh” Lake Ontario water. This is to be expected due to the 26’s under water profile which rises steeply aft. Ellis did an amazing job in creating a 26’ with the accommodation of a much larger yacht, 6’ headroom and pleasing to the eye. One of the compromises made was her under water profile that causes her to squat as speed and prop wash increases.
I believed that if one could cause cavitation between the hull and water the tendency to squat would be reduced. With this in mind, I stuck two stainless steel cowls over the waste outlets of the sink and head basin. (see photo) and a couple of copper ones over the cockpit drain outlets. I used 4200 to glue them on 3 or four years ago and there is no sign of them dropping off.( I did not wish to puncture the hull). My second modification was to convert to a standing gaff rig where the entire sail area is within 15’ 8" of the mast, reducing weight aft. I do not know how much this contributed to the effectiveness of the cowels. A standard rigged 26 installing cowel cavitators would answer this question. I do not know what the optimum size of the cavitators would be. I just used what was convenient.
FYI At the time of the observations Mascouche had:
Since the modifications, I have not been bothered by a sooty moustash appearing on the transom. The cowl cavitators do not compromise speed under sail.
Cheers,
John Newell
Mascouche 26C 1
Toronto
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