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Old 08-11-2012, 08:20   #1
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Which Engine?

As Tim the Toolman Taylor used to say. "More Power!!" I am debating between the Beta 20 hp and the 25hp. Difference in price is about $500.

My wife makes that much in one day of work as a nurse. So should I ask her to work an extra day so we can get 5hp extra or should we just be happy with the 20hp.
We plan on selling the boat in two years so the extra hp probably won't help me out too much or should I say for too long.
The alternator on the two engines is the same size (We've never run out of power before)
The new engines will come in close to half the weight of the old engine.
We aren't in a hurry to get anywhere.
Do you think one will be better then the other for resale (hard to quantify)
Running 3000 rpm (around 85% WOT) one engine produces 14hp and the other 17hp. I wonder how that translates into speed?

I really waffle on this one. I figure a days work is worth the extra hp . . . then I think if I am not going to get the money out when I sell it. . .

Thoughts anyone?
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Old 08-11-2012, 08:44   #2
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Re: Which Engine?

Download surfbaud sailcalc (google that, or search this forum) and find out yourself by entering in your boat's numbers. 14 to 17 is a 21% jump, so that is a bit more noteworthy than someone considering a jump from 38 to 41 (practically negligible). However, depending on your hull speed, if may not make much of a difference at all. Guessing at what size your boat is, I surmise this will get you an additional 0.4 knots...but you need to see for yourself with sailcalc. A more noteworthly consideration may be the cost of repitching your prop in order to match it to the new engine/gearbox...that may be $100-200 more, or $0 if you choose the right engine. Of course, even with these estimating tools, you may need some post-sea trial adjustments.
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Old 08-11-2012, 08:58   #3
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Re: Which Engine?

If nothing else that extra 5 hp would allow you to run a larger alternator while under way with little loss in propulsion power.
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Old 08-11-2012, 09:29   #4
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Re: Which Engine?

Charlie, If you are going to sell the boat in two years, then go with the larger engine. Most buyers are impressed by horsepower and the number of bunks. Neither of which are very important to a long distance cruiser. What brand and power of engine are you taking out? I am not familiar with your boat, but if you are going much smaller than the original engine, it might make the boat harder to sell. What about exchanging your engine for a remanufactured engine of the same make and model, and save yourself the costs of changing engine beds and mounts and all the small things that add up to big bucks. __Just some thoughts._____Grant.
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Old 08-11-2012, 09:46   #5
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Re: Which Engine?

For determining a speed increase it is not a simple linear relationship where you can do a ratio. To double the speed of a boat you need to roughly cube the horsepower. This means that 25-20/25 x 100 would not be a 20% increase in speed. It would be something less. Whether or not it is worth it is hard to say.

By increasing the horsepower there is also a chance that you may have to change the pitch and/or diameter of the propeller, so figure that possibility into your cost.

It's probably not worth it if the engine bed mounts need to be moved, Not for an additional 5 horsepower.
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Old 08-11-2012, 10:01   #6
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Re: Which Engine?

Neither is enough HP for the sceptre 41 IMHO, and will be a detriment when selling. There's a big difference in flat water speed calculations and fighting a 5 knot current and 4-6 foot wind waves. Nothing worse than a boat that just wallows and doesnt move.
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Old 08-11-2012, 10:11   #7
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Re: Which Engine?

Charlie,

Get the wife to work an extra week.
You have a 41foot boat. A 20 or 25hp is way to small

My Catalina 380 had a 40HP.

The Sceptre 41 in Yachtworld.com have 50hp engines.

http://www.yachtworld.com/core/listi...ng_id=1504&url=
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Old 08-11-2012, 10:17   #8
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Re: Which Engine?

Charlie if your in Cailifornia there is a new 38 hp yanmar @ minneys in Costa Mesa sitting on the floor for $7200.00. Looks sweet said it had 15 hours on it.
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Old 08-11-2012, 10:35   #9
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Re: Which Engine?

I have a Cooper 416. It has a 4-108 in now. When I spoke with a prop dealer he had some interesting things to say about prop size and horsepower. He said the Perkins was pretty much the goto engine for boats in our size. We talked about hp to turn altenators and prop size Right now I have 15x12 and he said that I might as well be turning a plate with 51 hp.He thought that I sould go down in horses and increase prop size and get the same speeds because I only run around 2000 rpms anyway.It takes hp to run altenators and by the time you add current and and additional power for seastate a 20 hp engine in your boat would go nowhere in a hurry. But he said that 35 to 40hp with a larger prop at curise would take the weight and wasted hp plus add kph. I am just going to rebuild my engine but change my prop because I have a 160 amp altenator.
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Old 08-11-2012, 11:44   #10
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Re: Which Engine?

Aloha Charlie,
I'd go with the larger. Newbie boat buyers are always impressed with "more power."
kind regards,
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Old 08-11-2012, 11:54   #11
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Re: Which Engine?

Thanks for the comments and I apologize that I didn't mention the type of boat. This boat is a Wauqiez Gladiateur 10m (33 ft). Seems like most people are saying to go for the bigger engine and my main argument against it is $$$$.
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Old 08-11-2012, 12:25   #12
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Re: Which Engine?

More money=more horsepower=better ability to stand up to adverse conditions
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Old 08-11-2012, 12:50   #13
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Re: Which Engine?

The conventional "rule of thumb" these days is around 2hp per 1,000 lbs. of displacement. This is a boat with a displacement of 11,500 lbs. So I think a 25hp engine would be just right. You could get by with 20hp, but future buyers would probably consider that a little bit (not seriously, but a little bit) underpowered.
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Old 08-11-2012, 13:02   #14
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Re: Which Engine?

Quote:
Originally Posted by Charlie View Post
As Tim the Toolman Taylor used to say. "More Power!!" I am debating between the Beta 20 hp and the 25hp. Difference in price is about $500.

My wife makes that much in one day of work as a nurse. So should I ask her to work an extra day so we can get 5hp extra or should we just be happy with the 20hp.
We plan on selling the boat in two years so the extra hp probably won't help me out too much or should I say for too long.
The alternator on the two engines is the same size (We've never run out of power before)
The new engines will come in close to half the weight of the old engine.
We aren't in a hurry to get anywhere.
Do you think one will be better then the other for resale (hard to quantify)
Running 3000 rpm (around 85% WOT) one engine produces 14hp and the other 17hp. I wonder how that translates into speed?

I really waffle on this one. I figure a days work is worth the extra hp . . . then I think if I am not going to get the money out when I sell it. . .

Thoughts anyone?

"Common sense" would suggest that you get the larger engine. I would say (having recently replaced an engine) do it IF your boat will respond to the increased horsepower. Will it give you anther 1/2 - 1 knot at full power when you really, really need it, say, getting to safe harbor before a storm, or helping you deal with a storm better? Slam dunk -- do it.

Second, I'm assuming the engine will fit in your engine compartment?

I had the choice of 15, 20 or 30. Only the 15 would have fit with no modifications, but 15 on a 31' boat seemed on the low edge of "enough" to me. The 30 would have required major modification to the engine compartment which would also have made it harder to use the already teeeeny galley, and I live on the boat.

A carpenter friend made a very simple modification to the front of that compartment and the actual footprint remained the same -- the companionway steps stayed where they were. 20 hp is *absolutely* not overpowered, and if I could have done 25 I would have.

You can use this to your advantage when selling the boat. It probably won't get you more for the boat, but it will also probably make the boat easier to sell.

Just my .02. If you need a new engine, when you get it you'll be singing "Happy Days Are Here Again!"
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Old 08-11-2012, 13:05   #15
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Re: Which Engine?

Go big. You will be glad you did in adverse conditions.
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