Motor power versus safety?

[Rich Songer]

My wife and I are new to the sailing world. In fact, we are considering making the Mac '25 (1983) our first try at learning the craft. I happened to discuss our potential purchase with a friend -- experience with V8 inboard on a 28(?) -- and he told me having a motor less than 75 hp would be dangerous on the ocean. When I asked why, he replied it was the docking and going against tide and currents that could see our investment end up in splinters? Is there some power ratio that I should consider when protecting our boat? Is there a maximum or minimum that should should be observed with the Mac '25? How dangerous is underpowering a sailboat of this size? I, too, will search where I can to find the answers to this area of concern, but I never thought it would be potentially dangerous. Does anyone have a place that I can find these kind of questions from a person new to the craft? Any guidance in this area would be greatly appreciated. Also, where do you go to find the "blue book" for sailboats?Sorry for the long post and many questions.Rich Songer

 

[Doug Rodrigues]

Sailboats Vs Motorboats

Your motorboat friend obviously knows nothing about sailboats. Sailboat hulls are of a different design, and for the exception of only one model cannot plane on top of the water like a motorboat. I own an '83 Mac 25. There is such a thing as calculated hull speed. My boat goes no faster with my new 6 hp four stoke outboard than it did with my old 8 hp two stoke. Also, the swing-down motor mount cannot handle the weight of a 75 hp motor, if that's what your friend may have suggested. The manufacturer originally recommended a 10 hp (two stroke) outboard as the maximum size for the Mac 25. Four stroke outboards are heavier...you'll have to determine the weight of any four stroke outboard you buy to be within the acceptable weight limits of the motor mount. But for what it's worth, the MacGregor boats are better used in inland waters, not the open ocean. It's been a while since finding that Blue Book for Sailboats web site, but it's out there somewhere. Out of curiousity, you may ask your friend how all those sailboats are able to go transpacific and transatlantic without benefit of an outboard?

 

[dan]

www.nadaguides.com

Hi Rich........This site will calc values for boats and motors.(for FREE!)The Mac 25 sounds like a good choice on a firstsailboat. You can enjoy the inland lakes.My 26X with 50hp Honda goes no faster with ballast in than what a 20hp would do at thisaltitude(6000'). The hull speed thing!The 26S(centerboard) is also a popular boat hereMaybe Doug can help us out on the sailingdifferances(water ballast/steel keel?)happy shopping

 

[Doug Rodrigues]

Read below: 26X flips

Read what J Cherubini had to say about sailboats in general, especially the concentration of weight, arm and freeboard. He pretty much explains it all, although with a bias toward displacement sailboats. Also, you can use your search engine and find "calculate hull speed." That sailboat can only go so fast because of the bow wave being pushed-up ahead of the boat.

 

[Mike]

The Nut

Here is the nut of the whole problem. With a displacement hull, you will achieve a given maximum hull speed. The only way to increase this speed is to provide enough power to force the hull up ontop of the water. More like a car tire hydroplaning. That kind of horsepower is going to blow the motormount right through the transom, it's not built to take that kind of force. If you could safely bolt on that much power, the weight would destroy any characteristic which makes the boat sail well.When buying a motor, remember that many waters are now closed to two stroke motors and many more soon will be. They polute the water, are noisey and waste fuel. I have a Honda 10HP four stroke that, though old, is reliable, quiet and has more than enough power to max my hull speed.Don't ask a power boater for sailboat advice. It's like asking a dog breeder what type of cat is best. They are both four legged fur bearing pets, but they are nothing alike at all.Happy Sailing.Mike