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Hey,

My Newport 28, around 7000lb, came with a 16 HP engine. I had a 2 blade fixed prob. I thought the engine had plenty of power.

I would think that 16-20 HP would be fine for a boat up to 10,000 lbs.

Barry
 

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IMHO, that's nominal. Personally, I'd go a tad bigger; Justin case ya need to get out ta Dodge right smart;)
Given that most are not really labeled at. true,, normally use able HP; mebbe something in the 25-30 HP range?
Facing head-on or.building seas, nasty increasing wind on the nose, aand a need to get to that hole. quick? Mo'is better :D

Factor in the possibility of engine-driven adsons and your HP output quickly gets eaten up.

Plan Aheab
 

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Don't call me a "senior"!
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For a 9000 lb boat you could probably get away with a bit less power, maybe 14 to 16hp. But 20 hp wouldn't be terribly excessive, IMHO. It would probably be a good idea to take a long, careful look at the available engine space, and how you are going to get to the various bits when it's time to service the engine (filters, zincs, water pumps, priming gizmo, etc.). On many boats of that size a 20 hp engine would be a pretty tight fit and/or make servicing an almost heroic task. A slightly smaller engine might make things just that much more tolerable.
 

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FWIW, my 6-ton classic was originally fitted with a Henry Meadows 25hp donk. 20 years later the owner upgraded that to a 35hp Peugeot. Fast forward another 20 years and it's fitted with a 40hp Volvo and I now find I can tow an S&S30 (~5 ton, I suppose) plus a Tumlaren (another 3 tons?) at hull speed without even hitting maximum revs. :cool:

So, methinks 20hp will be fine for your lightweight flyer.
 

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Question from a newbie-Why are sailboat engines so small HP wise ? Is it size as earlier mentioned ? Or just a desire to not move quickly ? I think it's great cost wise as motors are through the roof costwise but as a power boater it made me wonder.I currently have 3 boats and the smallest is a 16 ft wooden boat skiff I built with a 25 hp outboard and I'd honestly like to upgrade that,seeing these big sailboats with 9.9s and 15 and 20 hp has me stumped
 

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Hey,

It's really very simple: Sailboats have displacement hulls. Meaning that a sailboat can only go so fast (and not very fast at that). The length of the waterline determines the top speed. My O'day had a 29' waterline length and hull speed of about 7.2 kts. The stock 21hp engine could push the boat at that speed. If I put a 50HP engine in it still would not go any faster. Even a 500 hp engine wouldn't help the boat to go any faster. A bigger engine would just make a bigger hole in the water since the boat can't get up out of the water but must push the water aside.

Most powerboats have planing hulls. Meaning that the boat can get up out of the water and ride on top of the water. A planing hull is not limited in top speed, so more HP = faster speed.

In reality, a sailboat can exceed hull speed, but not by much and a bigger engine maybe helpful in conditions like high winds and waves. But the difference is pretty small, like a 30HP engine instead of a 24 HP one.

Barry

Question from a newbie-Why are sailboat engines so small HP wise ? Is it size as earlier mentioned ? Or just a desire to not move quickly ? I think it's great cost wise as motors are through the roof costwise but as a power boater it made me wonder.I currently have 3 boats and the smallest is a 16 ft wooden boat skiff I built with a 25 hp outboard and I'd honestly like to upgrade that,seeing these big sailboats with 9.9s and 15 and 20 hp has me stumped
 

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Hey,

It's really very simple: Sailboats have displacement hulls. Meaning that a sailboat can only go so fast (and not very fast at that). The length of the waterline determines the top speed. My O'day had a 29' waterline length and hull speed of about 7.2 kts. The stock 21hp engine could push the boat at that speed. If I put a 50HP engine in it still would not go any faster. Even a 500 hp engine wouldn't help the boat to go any faster. A bigger engine would just make a bigger hole in the water since the boat can't get up out of the water but must push the water aside.

Most powerboats have planing hulls. Meaning that the boat can get up out of the water and ride on top of the water. A planing hull is not limited in top speed, so more HP = faster speed.

In reality, a sailboat can exceed hull speed, but not by much and a bigger engine maybe helpful in conditions like high winds and waves. But the difference is pretty small, like a 30HP engine instead of a 24 HP one.

Barry
Is it their weight of the boat or the design that makes it a displacement hull ?
 

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Discussion Starter · #12 ·
rapp :

It is because the boat is digging-in to the water and cannot plane.
Laying on extra power does not help much to go much faster than the so-called "hull speed". It goes a bit faster, but not much.
The bigger engine helps in fighting wave slap and wind loading, but the water speed does not rise much after hull speed is reached.
If it were a speedboat it would bounce up out of the water and will go ever faster when more power is applied. Indeed it can take off if you are not careful.
A displacement hull goes a wee bit faster but just digs-in deeper to the water, really.
 

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There are (or at least were) a few designs that could get up on a plane, if fitted with a big enough engine. For sailboats they are pretty good powerboats, and for powerboats they are pretty good sailboats. But either as purely a sailboat, or purely a powerboat, they're nothing to brag about.
 

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There are (or at least were) a few designs that could get up on a plane, if fitted with a big enough engine. For sailboats they are pretty good powerboats, and for powerboats they are pretty good sailboats. But either as purely a sailboat, or purely a powerboat, they're nothing to brag about.
I've seen those McGregor boats,is that similar to what you're talking about ?
 

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I've seen those McGregor boats,is that similar to what you're talking about ?
Yup.

There used to be a M26 docked next to our boat. He could get that sucker up on a plane and do maybe 20kts. But our Ericson 27 (not a particularly fast boat) could sail circles around him in any winds above about 10kts.
 
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