Engine Size: Whaddya Think?

[AWKIII]

I really appreciate everyone's input.

Looks like we probably have the makings of two models here. Both would have a beam between 8.6 and 9.0 and one would be at around 28' and the other, 32'.

Now comes the can of worms.....engine size.

The power or motorsailer isn't a concept that MacGregor invented. They have been around for years. Dick Valdes, the founder of Columbia Yachts, started Lancer Yachts back in the 70's which featured a complete line-up of powersailers. Their most popular model was a 27 footer. Although the concept is viable in large yachts and the ULDB MacGregor 65, it has never been perfected with small, trailerable boats. There is a lot of compromise and what you normally find is a boat that will not sail or power exceptionally well.

Time to open the flood gates on this one.

We are back at the boat show. You stumble upon an exhibit with TWO hot new trailerable sailboats. One at 28' and the other, 32'. They both have a nice open transom and huge cockpit. Despite their size, they both are carrying outboard engines with engine controls to an Edson steering system.

The question:

What is the smallest engine you would find acceptable for this boat?

[Currie]

Hi Art,

This one is tougher than the other questions. My answer would be - I would want the answer to be engineered and tested by the designer. The *maximum* HP for a displacement hull would be about powering against wind and waves in inclement weather (as opposed to top speed which is naturally limited). But, the *minimum* HP is based on the same thing. What's the worst conditions that the boat can safely power through? I guess I would need to know the boat (hull, displacement, drag, etc) to really be able to answer that one. I'd want the factory to design and test and not allow sale of a new boat within anything less. If I had to guess, it would be somewhere in the 20HP range for a min. but again, not sure. I know, what a cop-out answer

Cheers,
~Bob

[aya16]

The cart before the horse I think, what would the expected performance want to be? some 28'-32' foot motor boats get up to 200+mph, with 1000+hp in them. a hybrid sailboat (motor/sailor) would be considered a good performer by me that sailed well and achieved 25+mph. So what would it take, hp wise to achieve that? 50-90-100-200hp? wouldnt matter as long as it performed the way it was designed to.

Thats where mac has the cart before the horse too, they design a boat that should reach speeds of 24mph yet try and restrict the hp to a 50 that will never achieve that in real life, I think they should have set the goal of the speed and built the boat to handle what ever hp it took to achieve that speed. The mac does handle well at those speeds, and the length is about right for the ocean to be a comfortable ride in a normal swell at that speed. But were not supposed to put an engine on to achieve those speeds.

I dont know I think with the mac and a few others its all been done, either the factory made a boat that uses a powerful outboard, or the owners modified their boat to get the performance that mac designed into the boat.

Now you really want to be different, how about an inboard jet, like in the jet ski's, at around 120hp (small and compact) that will get your boat up to 25mph easy. With the jet you dont have that huge nasty outboard hanging off the back, it looks more like a sailboat, and probably sail better. The cost of the jet is half what an outboard would cost. Plus a swim boarding platform in the back now over the jet nozzle. With the rudders at slow speeds the new sailboat would turn on a dime with a jet, unlike the power boats that have jets. you do want a performance sailboat right?
Mike

[Gazmn]

What's the smallest Saltwater E-tec they make

Because of where WE come from, a hybrid, we want something that gives us options when the wind is down.
But I'm not talking tubing here. 2 years ago a did a week on a Hunter 44 in a "Learn to Sail/Cruise" in the Gulf - in August .

My bad - because There's no wind in August in Florida and the Gulf was as warm as puke. Not knocking Florida - I just wish I Knew enough to have opted for The BVI since I was already spending money I didn't have to get my wife into sailing.

Anyway, what sucked the most was motoring @ 5 - 6kts on the Intracoastal where EVERYONE else is blowing by you in powerboats. Boy I wish I had my with me

So can we find a way to:
1. Beat hull speed - since you have a motor.
2. Make sure you have enough balls to go against the current on say the East River & hull Gate in NYC. - You know I'm not saying "hull". These can have currents as High a 7kts.[guessing ]
b/c time and tide wait for no man & sometimes you Have to get home.

so minimum 40HP
That's for Balls not hull speed

[Hamin' X]

Assuming that you are not going to be redesigning the hull to a semi-planing one, 25 HP should be more than adequate.

~Rich

[Love MACs]

I would think, but then what do I know, that the smallest engine limit would entail the ability to counter medium currents (3-5 knts) and out "sail" the sails as in running from a storm. So not being a nautical engineer or an engineer of any kind I would think that a minimum of 35hp "should" accomplish that. But would be happy to hear from the experts that a smaller engine would accomplish same.




Allan

[AKCoastie]

Well from my flight school days there was the lesson on the relationship of drag to lift and thrust. Basically there is a non-linear relationship that limits top speed due to increased drag. Once you get to a certain speed, the induced drag increases exponentially so that it requires an ever increasing amount of thrust for a smaller and smaller increased amount of speed. I am assuming that the hull of your new boat is already laid out. That being said, there is a max speed that it can go before the drag means your burning ungodly amounts of fuel to go faster. Sooo...
I would like the boat to go 15 or even 20 knots if feasible. I would like it to do that at about 75-85% power. Whatever engine size that works out to is what I want. I am guessing it's going to be an outboard so a diesel is out of the question, plus a diesel is going to push the price way up.

[Hamin' X]

First, assume that this boat is a displacement hull. Next, plug some figures into This Calculator.

Looking at a 5,000 Lb displacement and 30' LWL, you find that the max hull speed will be about 11.4 kts and that it will take 1,100 Hp to achieve that. Drop the speed down to 8 kts and it only take about 15 Hp. Want to go 9 kts? It will take 33 Hp. 50 Hp will get you to less than 9.5 kts. The point of diminishing returns seems to be between 8 an 9 kts. This will never be a power boat, so 25 Hp should handle all the current and wind that you are likely to encounter.

~Rich

[pokerrick1]

I'm going to answer the question -- - 50 ETEC on the 28' - - - 60 ETEC on the 32'. I'm not looking for speed here, just fuel efficiency and the ability to get through 5 to 7 MPH currents without killing the engine or my hearing

Rick

[bscott]

What ever HP that can get the boat fully loaded on to a true plane at 80% (4,000 rpm) power. For a semi-displacement 28' X 8'6" Mac hull that might be an E-tec 90. If this boat is not a hybrid, I would not be a customer.

bscott

[Billy]

The question:

What is the smallest engine you would find acceptable for this boat?

I, too, would only be in the market for a powersailer. Since I have run 140 hp for 7 years on my , it would be hard to give that up. I just can't go back.

[Kelly Hanson East]

I would like to see it rated for a 25. Per the above thats on the diminishing returns curve of HP for speed.

(and please dont go through H(e)lls Gate in NYC without local knowledge on board.

There is also a steep price curve on motors too, although thats a small percentage of boat price

9.9s are 2k, 40 HP are 5k, and the 15 18 20 30 are strung out in between.

Goes without saying that I would want long shaft, power trim, electric start, CDI Ignition, and 4 stroke EFI of course.

[AWKIII]

Thank for the input!

Once again, it was well thought out and it helps tremendously.

The hot new boat you saw at the show will be 28' to 29' in length and carry an 8'. 6" to 9' foot beam.

She will be capable of carrying a 25 horse outboard.

One last question.....

[Adam Jacobsen]

The question:

What is the smallest engine you would find acceptable for this boat?

I, too, would only be in the market for a powersailer. Since I have run 140 hp for 7 years on my , it would be hard to give that up. I just can't go back.

Billy,

Can you give us more information on your experience with using such a large motor? Such as:

How fast can you go?
Does the extra weight affect sailing?
Any problems with motor mounting or clearance?
Is the hull structure adequate to hold the weight of the large motor?
What kind of mileage do you get?
Are the two standard gas tanks adequate for the average 1-2 day trip?
Any other considerations?

Our local dealer doesn't recommend anything over 60 hp on the 26M. I'm very new to the powersailing world and (when I get a Mac) would like to have the ability to keep up with my friends' ski boats when needed. If there is a previous discussion about this, maybe someone could direct me to it.

Thanks!

[Kelly Hanson East]

Art - Im pushing my recommendation up to 30 HP

If I can make 5 kts against a 5 kt current, then I cover any sit in the NE that I can think of.

30 HP is incremental cost over a 25 HP of course