Poor performance under power

[Warren]

As we near a dreadful sailing season here in the northeast I have a nagging problem with my boat under power. First season with a 1989 Catalina 30 Tall Rig. I have the Universal M25XP, two blade prop I think it is a 13RH 12P. I get around 3200RPM out of the engine, however I cannot get above 5 kts, and in some sea conditions under 3kts. Since the first week of owning the boat my speed indicator has not operated so I am basing these numbers on both a mounted and handheld GPS. I have had a leaking packing gland that I have been able to get under control, until I re-pack it over the winter. Before I have the boat pulled in early November should I have a mechanic take a look, or will they be able to tell what the problem is after the boat is hauled. From reading the postings on this and othe sites, this boat should be able to obtain much higher speeds under power. The other variable is the bottom condition. I was not given a say in what went on to the bottom (long story) but they used the worst paint possible. I hope I do not offend anybody but Petitit Unepoxy, I watched the yard slap it on every bottom in the place. I know the condition of the bottom can greatly effect the speed, but under sail in moderate winds (10-15 kts) I can get 5kts easily. Any advise would be appreciated.

 

[Bayard Gross]

I don't like Petit Unepoxy either

I do not know if you sail in Long Island Sound or the south side of Long Island.If in Long Island Sound as I do, then Petit Unepoxy is definitely insufficient for the fouling that occurs, due in much part I beleive to the warm nature and nitrogen pollution of Long Island Sound.Petit Unepoxy is also a modified epoxy which not only lasts just one season, but as a modified epoxy is difficult to sand off when you utimately need to.I would use a Petit abalative with their version of a slime blocker. Expensive stuff especially if painted on by a yard that will charge you far more for the paint than if you bought it yourself.I think that maybe your propeller has become fouled, a normal occurance by this time of the sailing season especially with a fairly weak copper content anti-fouling paint as Petit Unepoxy.

 

[Chris Burti]

Poor performance

Next time you go out on a light wind day, check your speed with the GPS by going a mile in one direction and then a mile in the opposite direction. Your GPS is measuring your speed over the ground and that may not be a true reflection of your auxillary system's performance.If that checks out, I think the most likely probability for a cause of poor performance may be the hull condition, since you probably should do better than 5 knots under sail in those wind conditions.

 

[Randy]

Poor performance

There are a number of things to check out. First, as has already been suggested, a fouled bottom will really slow you down. Next, a fouled prop won't provide the thrust you need for reaching hull speed. Double check the size of the prop to make sure it's the proper match for your engine/hull combo. Also, you say you're getting 3200 rpms, but is the tach accurate? An inaccurate or improperly calibrated tach won't display the correct rpms. (You may only be turning 2500rpm, for example.) Still, I think it's more likely that you've got a fouled bottom or prop. Let us know what you find.Randy

 

[David]

Similar Situation

Before I had my bottom job done this year, I was only able to make about 4.5 knots under power with the same engine (3 blade prop) and rarely saw five under sail. After the bottom job, motoring speed is up over 6 and sailing speed is over 7. Get the bottom done if possible