6hp doesn't cut it in a strong river current

[jim solari]

I travel out the mouth of the merrimac river to get to the ocean. If I miss my timing and am coming back on an outgoing tide I may bee fighting as much as a 3-4 knot current. I have a johnson 6 hp 1991 which runs pretty well BUT against this current I just barely make way. My normal 1hour commute to the dock is now 2 hours I think I would like to get a 9.9 hp outboard but i don't know how much faster it will go. The other question is 2-stroke or 4-stroke for dependability and durability

 

[Don]

Boat Speed

Generally, a motor will not push a sailboat past it's hull speed. On my Venture 25 I had a 9.9 Johnson longshaft 2 stroke and I could only rev it to somewhere between half and 3/4 throttle, because anything higher my boat would try to plane. When the boat tries to plane the bow will rise slightly and the stern will sink causing the motor to submerge and thereby slowing down the boat. So increasing horsepower may not solve your problem. The rated hull speed for a Catalina 25 is 5.9kts so I have to assume that for a Cat 22 it is less. If your fighting a 4 knot current this only leaves you 1 maybe 2 knot in actual boatspeed(SOG) which isn't a whole lot.

 

[Ted]

Go close to shore

The current is less near shore. A bigger motor will help somewhat, but as the previous post mentions, there is a limit to the boat speed.I go through Woods Hole on occassion, and one time saw a 35 footer just standing still against the current - motor wide open. It took him a few minutes to gain any distance. I also saw a small boat under sail going against the current making good headway. He was about 20 feet from shore.Regards,Ted

 

[Ken Cobb]

testing

You can test what your maximum speed us under motor in calm water. If that speed matches your maximum designed hull speed, then you already have as much motor as you can profitably use.

 

[Tim Pinkham]

More Power

Jim,My boat is moored four miles up the Piscataqua River just a little north of you. The out going tide/current flows atnearly 6 knots. I think the Merrimac probably flows at about the same rate.I put a Yamaha 9.9 four stroke high thrust on my C22. It is very heavy for that small a boat but it sure has come in handy against the strong currents.If you end up getting a new motor I would definitley get the four stroke no matter what size you end up with.They are heavy but quiet and easy on the gas.Tim Pinkham~JUNE II~Dover, NH