Fighting the Current

[Bob Gulbrandsen]

I have a Catalina 1985 27 Tall rig in a Marina in Charleston Habor. She has a 2 blade stock prop. My problem is due the very swift tide it can be a problem docking the boat with any control . Would the change to a 3 blade prop. be to my advantage , and would this effect the cruising speed of the boat ? At present in reverse and the tide apainst you you have little or no way to steer the boat. Whats the answer guys ?

 

[Mitch Witt]

some help

Hey Captain, we have a 42 beneteau also wiht 2 blade prop and with similar lack of power problems in some situations. Be careful not to get into dangerous situations where your lack of power puts you at risk of collision with commercial traffic or obstacles. After 8500 nm in caribbean and bahamas we are considering a 3 blade. The main consideration:Check your motor mounts, may need new ones or beef up of their mounting as a 3 blade prop will place more torque and more stress on the motor mounts (and your transmission). We have used our 15 hp dinghy motor mounted on the dinghy, secured to the stern to give us more push when entering/leaving inlets or when necessary to motorsail on a close reach. Example: ever sailed out of Wynah Bay east of Georgetown SC? The extra push of the dinghy motor, with the perkins going full speed and all sails set was the only way we could exit one morning in seemingly calm conditions. Near the end of the jetty the seas were running 8' into the forward port quarter. Watch those cross currents! Good luck.

 

[Larry Watkins]

More power

Bob; You and Mitch might be suffering from the same ailment, i.e., your prop is not putting the engine's horsepower in the water. Check your sizes against a published table and you'll probably find you need more pitch or another blade. I have a Beneteau 40 with a 50 hp Perkins turning a 3-blade Max-Prop and have plenty of push under power. A two-blade prop can be re-pitched for not a whole lot of money.

 

[Ron Sheldon]

to help fight the Current

In regard to your question and the responses gotten. I would have to say..Go for the 3-blade prop. If you were racing and trying to get the maximum from your boat then go for a feathering 2 blade or have them "Tweek" your old one for the best pitch etc. I have had 3 boats over the last 10 years. (an 84 Ericson 28+, 85 Islander 30' & 34 Hunter) at worst case you lose about 1/2 a knot..(really...that is all!! I lost more than that by not cleaning my bottom!)I actually checked in similar conditions with a GPS. But the added push you will have is amazing!! & add to that the torque in reverse?...My gosh. On the Ericson I had a folding prop and we used to really bury the railings. But motoring we sometimes joked we could get out and push faster.and in a current had almost no control!! After going to a 3-blade...you could feel the difference and as far as sailing you really couldnt feel much differance. the only way was by really checking the GPS while heeling. So I would do it..as a matter of fact I did...3 times!!Just give the guy at the local prop shop your engine hp at rated RPM, hull speed and shaft size. he will tell you what prop to get and if you are on a budget you can get a used or better yet a reconditioned(balanced) prop for about $150.00!Good luck and great sailing (and motoring!)RS

 

[Kevin l. Woody]

Three blade

Hello Bob,I would consider a three blade unit. You can expect at least a thirty percent increase of efficiency over a two blade. You should experience additional control and additional response time, which sound like you need. The problem you will experience is the increased drag of a fixed three. Your boat is slowed currently by the two blade by apx. 8-10% the three blade will increase this to 15%+. Of coarse you will need to remember that the boat is not aware if it is in moving water or not. Our only reference to speed is our relationship of a moving boat, moving water and earth fixed objects. What I believe we need for increased efficiency is increased response time with our propulsion unit. The three blade will give you that. Hope this helps. KevinSorry for delay in response from me, I was attending a boat show in Oakland.