Is my sailboat overpowered?

[Buddy_Y]

Hi All:

I just purchased myself a 1974 C&C 30, in part because it had a new Yanmar installed in 2005. During the sea trial, I noticed that the tiller required a firm grip when the boat was under power, since there seemed to be quite a bit of force acting on it at cruising speed. So much so, in fact, that you basically had to brace the tiller against your thigh. This surprised me, but I’m a newbie and my last boat was a Catalina 27 with an 9.9 outboard mounted aft of the rudder, so I just assumed that I lacked a decent frame of reference.

Sure enough, however…. The deal closed last week, and today the broker was to deliver the boat to the mainland from Vancouver; however, he had just left the harbour when the tiller broke off in his hand. (It left enough of a nub for him to return safely.)

My question: is the boat perhaps overpowered? Historically, the C&C 30 mk1 originally came with an atomic 4, and later had an optional Yanmar qm15 and subsequent to that a Yanmar 2gm, which I believe were 15hp and 13hp respectively. My boat’s 2005 engine is a Yanmar 3YM30, with 29 hp. (It has a full three-bladed prop, i.e., not a sail prop.) I’m wondering if the water flow from that 29 hp is going to be exerting too much force on the rudder/stock/tiller?

(Some Background Details: The previous owner was a nice fellow, but confessed himself to be not very knowledgeable about boats. He reported that proper cruise was 3000 rpm out of 3500 rpm; this slightly surprised the broker, who had guessed that it would be about 2800 rpm. The mechanic and surveyor I hired did not grouse about the engine, and it was ostensibly installed by a reputable shop. C&C 30s displace 8000 lbs. This one has the original swept-back shark-fin rudder.)

Cheers,

Buddy

p.s. The C&C 30 stats are here.

[CSY Man]

Nah, 29 HP for a 30 foot boat is about right.
If there is too much pressure on the tiller, just ease off on the gas..

How does the tiller feel when ya sail at the same speed?

[Weyalan]

You may have more HP than you need, but this doesn't necessarily need to be a probelm. It is my understanding that hp is, approximately, directly proportional to engine speed, so you can simply reduce revs to reduce hp.

The maximum speed that your boat will do under motor is related to the waterline length. (i.e approx 1.34 x squareroot of waterline length), so if your Cal 30 has a waterline length of, say 24 feet, then your maximum motoring speed is about 6.5 knots, and all the engine and prop in the world ain't gonna push it any faster.

Having hp to burn does have the advantage, in a cruising boat, that you can use that extra hp elsewhere - like a high amp alternator for charging batteries, or engine driven refrigeration or engine driven hot water.

[Chuck Baier]

Buddy, Was the boat hauled and the rudder inspected during survey? It could be a bent rudder shaft since the rudder on the C&C is prone to damage on groundings.

[Tellie]

I'd suspect rudder damage as well. 3000 rpm also sounds right as yanmar diesels like to be run hard.

qoute....(and all the engine and prop in the world ain't gonna push it any faster.)

I always wanted to drop a full blown Chevy 426 ci into a Cal 30 to disprove that hull speed nonsense. <grin>

[Vasco]

If I remember right the C&C 30 has an off-center shaft. Could this have anything to do with it?

[Pblais]

I doubt the engine is too large tough a little larger may be possible. Mine is on the large side but it's not a problem unless I like to burn extra fuel without much speed increase. The bill at the pump cures that problem quickly.

A tiller that breaks off was a bad tiller. Any force that can break a tiller didn't come from the engine unless it was more than half broke to begin with. As far as the prop goes I would get the ID of the tranny and the engine and go to a prop shop. They can tell you what prop it should have as a 3 blade. Sometimes people think they can out smart the proper propeller and usually lose. Propellers are a very exact science these days. On flat water you should reach max engine RPM's give or take just a tiny bit.

[Buddy_Y]

Hi All:

Thanks for the wisdom! I'll definitely make certain to check if the rudder shaft is bent. Notably, the boat was out for a survey a week ago Friday, and neither I nor more surveyor noticed anything about the rudder shaft--but then again, we also didn't notice anything about the tiller either.

I'm definitely looking forward to getting some experience with the boat and seeing how it performs at different RPMs. If I'm interpreting the group's wisdom correctly, running the eingine at 3000 RPM shouldn't be a problem, but running it a bit slower shouldn't be a problem either as long as the boat's still attaining hull speed. One thing I'll definitely check for is whether there's any stiffness at low-speed or when sailing, which would suggest a binding in the shaft.

I think the prop is probably okay--it was custom made by a well-regarded island prop shop, and it was they who designed it, not the previous owner. Additionally, the surveyor complimented it as a proper prop.

Alas, one of the annoying things about the situation is that this week I'm writing 'comprehensive exams' for a PhD, meaning that I can't take a day off to travel from the mainland out to Vancouver Island where the boat is located. Thus, I'm stuck just telling the broker "Just fix it and get it over here," and he's super busy at this time of the year, and the people who would be making me a new tiller are busy, and the stores where I could get a ready-made tiller (i.e., Westmarine) that might fix are on the mainland.... Sigh. Oh well, all it will take is time, effort, and money.

Cheers to all!

[Pblais]

Oh well, all it will take is time, effort, and money

Sounds like you understand well enough to me. You can add luck to the list. It still counts. You never know when a favorable bounce heads your way.

[David M]

Its the rudder. If it is pulling to one side then it is clearly bent. Any naval architect worth his salt is not going to design a boat with a rudder that pulls strongly to one side when the boat is flat and under full engine power.

Also, some sailboats can exceed their hull speed....when they start to plane.

[SVDistantStar]

How about a 40hp outboard on the back of a 36' Pearson, think thats overpowered? I dont have an inboard motor. I do have a 50hp Perkins diesel that i thought about installing, but that would be a bit over powered, not to mention the fact that i would lose part of my galley to fit the monster.

On another note, if anyone knows of a decent Yanmar 2cyl diesel for sale around GA/SC/NC, let me know, im in search of one.

[Pblais]

I have a 64 HP Westerbeke on a 36 ft boat. It's only slightly over powered but comes in handy at times.