I just purchase a 1978 Hunter Cherubini 25 and am trying to decide what type of auxiliary power to purchase some people tend to think 4-6hp is best and that anything larger will through the balance off on the boat. And I have read other reviews which tend to indicate this particular boat is heavy and thus its better to get a 9.9 or 15hp. Any suggestions. I've been a power boater up to now and thus more hp (15hp) is what my mind is telling me, however, any advise would be appreciated.
engine hp on 25ft cherubini
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We had a H'25 back in th 70's. I purchased it new. We had a 9.9 Honda long shaft and it was actually perfect. I don't think you would want a 15 (don't need the weight & additional torque) because you need to lift it out of the water when sailing too. We used ours in an area where we had some good currents and it worked fine.
Get a quality mount (see the current post regarding mounts) and you will be a happy camper.
Get a quality mount (see the current post regarding mounts) and you will be a happy camper.
I have a 9.9 on my 25.5 and have found that it is more than adequate. A 15 would be to heavy. Waste of power and gas. The boat only goes a certain top speed.
I have owned a Mac 25 swing keel with a 9.9 Johnson Sailmaster 2 stroke and a Hunter 26 water ballast with a Honda 9.9 4 stroke. I don't think I ever had either of these at full throttle. I bet 9.9 would be more than enough for your Hunter. Probably 6 hp would be enough. That said, I have been a lot happier with the 4 storke, than the 2 strokes, because of the smoke and stink, and electric start is great, and an alternator is pretty darn nice too.
Just for reference; the next size up Cherubini (H27) has almost twice the displacement (7000 lbs) as your H25 and came from the factory with an 8HP diesel. I never had any problems power wise and rarely, if ever, needed full throttle.
Cheers,
Brad
Cheers,
Brad
That is true but since it is a diesel it has way more torque therfore it is capable of turning a prop of larger diameter and greater pitch. But yes a 9.9 should be more than enough.
The rule of thumb i use for power is 2hp for every 1000lbs of displacement. You can go a little less than that, but I have found that to work quite well.
From a former dealer perspective.
When sailboats were or are designed, the standard max power taken into accout goes up to 10 hp only. Therefore, the transoms are designed with a max 10 hp rating. Anything over that is putting stress on the transom.
As many have said, the 9.9 hp is substantial. I found with many boats in the 26 feet and down this was true. If I throttled up to full power, the bow would raise up causing the boat for all intent purposes to slow down as you are in affect creating resistance. Simply put, this is not a planing hull but a displacment hull.
A 15 hp will not get you going faster and it is not designed for use on small sailboats. Also, most outboard motor brackets only take up to a 10 hp and you can go and check this out.
crazy dave
When sailboats were or are designed, the standard max power taken into accout goes up to 10 hp only. Therefore, the transoms are designed with a max 10 hp rating. Anything over that is putting stress on the transom.
As many have said, the 9.9 hp is substantial. I found with many boats in the 26 feet and down this was true. If I throttled up to full power, the bow would raise up causing the boat for all intent purposes to slow down as you are in affect creating resistance. Simply put, this is not a planing hull but a displacment hull.
A 15 hp will not get you going faster and it is not designed for use on small sailboats. Also, most outboard motor brackets only take up to a 10 hp and you can go and check this out.
crazy dave
Displacment of the boat is roughly 4,500lbs. so guideline of 2hp/1000lb displacment formula you 4500/1000 = 4.5 * 2 = 9hp
So anything over a 9.9 will be a waste of fuel, weight, money. You would be fine with a 8hp, but in heavy weather if you need to power through some rough seas, the extra 2hp of the 9.9 would be useful.
So anything over a 9.9 will be a waste of fuel, weight, money. You would be fine with a 8hp, but in heavy weather if you need to power through some rough seas, the extra 2hp of the 9.9 would be useful.
Just FYI regarding prop diameter. There are also issues with inboards having the ability to turn a larger diameter prop. When sizing a prop for an inboard the distance between the prop tip and the hull should not be less that 15% of the prop diameter. If it is less than this is causes all sorts of issues with prop walk a cavitation.
What normally happens that more pitch is used to compensate for the lack of diameter.
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