[quote=davefarmer]I second all that Damon says about motors on cats, they're not a substitute for sailing skills. And in my exp1erience, an 18 footer is the smallest boat I'd consider putting one on, it's additional weight in not a good spot, if we're talking off the rear beam. I can be compensated for to some degree by keeping crew weight a bit more forward.
All that said, I've put 2 and 3 hp two strokes on half a dozen cats, mostly 20 footers or bigger. I keep the boats deep in a protected bay on Flathead Lake in NW Montana, and it blows 10 to 15 out on the main lake nearly every morning in the summer, and I want some of it. So I motor fifteen minutes out to pressure regularly. And having a motor emboldens me to sail great distances from home, knowing I have the ability to get home should it shut off. Which it often does, I'm often chasing wind that might only last and hour or two, and having a motor increases the number of sailing hours I get in dramatically.
I had an older 2 hp Evinrude on a Mag 18 that would push the boat a 5.5 kts in flat water, not really enough power to maneuver reliably in big air, sailing skills needed there. I generally have a sheet metal/machine shop fabricate a mount for me, usually under a couple hundred bucks. The arm that extends from the mounting plate to the nearly vertical motor mounting piece needs to be hinged at the beam end so that the motor can be raised beyond the normal motor tilt, otherwise the lower unit will drag frequently. The design I've settled on has the arm in a short channel at the mounting plate that contains the arm, that I can slip a wooden wedge into when I pull the motor(and arm) up. The wedge stays in place with the weight of the motor on it, and is secured to the mounting plate with a small line so I don't lose it when the motor is deployed. The wedge holds the arm a bit above horizontal, enough to get the lower unit horizontal, which is enough to clear most waves. This puts the powerhead pretty close to the tiller crossbar, so some diligence is required when flipping the tiller extension from side to side when tacking.
I generally use 3 hp two strokes on the SC20s and the ARC22, which also produce 5 to 6 kts of boatspeed in calm conditions. I can often find lightly used 10 year old two strokes trolling motors for three to four hundred dollars, and they seem to last forever in this kind of service. I used a 2 hp Honda on a 20 once, liked that it was quieter, but it was a bit slower, and noticeably heavier. Newer models might be lighter. All the 3hp and smaller outboards I've used have had integral gas tanks, containing 1 to 2 quarts, with run times around 40 minutes at 3/4 throttle. I have strapped a 1 gal can to the tramp for long distance travel/delivery. I often use my ipod and ear defenders over the earbuds for longer stretches.
I've toyed with ways to mount a motor off the front beam, as many of the small outboards rotate 360 degrees(no reverse on most, some have a neutral), but have never mastered storing them in the raised position in a way that doesn't interfere with jib/jibsheets. Might be possible, certainly a better place to carry the weight.
When capsized, the motor is well clear of the water. I did turtle the ARC at the very end of the season last year( quite a story in itself), and after rescue, pulled off the carb and cleaned it, drained the fuel tank(integral), pulled the spark plug and ran lots of oil thru the cylinder, and it runs just fine now.
So motors add to the complexity of the sailing experience on a cat, but if your circumstances cry out for one, they can be managed. Just don't expect them to get you out of trouble in a blow, they're not enough power to overcome all the windage a cat offers, even with the sails down.
I found a few shots of one fabricated for the SC20 here:
http://www.thebeachcats.com/pictures?g2_itemId=112360
Dave<!-- editby --><em>Edited by davefarmer on Dec 13, 2014 - 08:11 AM.</em><!-- end editby --> [/quote]
