Can someone tell me if I will get much more speed when I am motoring my Catalina 22, if I have the swing keel in the up position? Thanks, Wayne
keel up for speed when motoring?
- Thread starter Wayne Spanier
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We did several cruises with the old style swing keel where we had no choice but motor, honestly we could tell no difference whether it was up or down, other that boat stability.... We used a 5hp Nissan which more than pushed the boat at hull speed, in fact we rarely used the throttle above half throttle.
I find that the keel up means less work for the engine. You can get the same speed with it down but you have to use a little more throttle. Physics doth rear it's ugly head.
Unless the seas are rough where you need more stability than crank her up and save fuel.
Unless the seas are rough where you need more stability than crank her up and save fuel.
I've used 3.5 hp to a 9.5hp and speedwise there isn't much difference. The difference is that the little guy will be wound out max and the big guy will hardly be working. At full throttle the 9.5 will just blow bubbles out back, not increase speed. Even on the bigger boats with inboards everyone has discovered there is a max hull speed regardless of hp. Those MacGregor26X sounded real cool when they came out, but the only waterskiiers they ever pulled were monkeys and squirrels, and they had 50hp.
Hey thanks for all the advice. It makes sense that cranking up the keel will save fuel but not increase speed. Waterskiing squirrels?
If the keel is up or down the surface area of the keel in the water is the same basically.
The leading edge of the keel is reduced in the up position but that does not seem to offset the fact that keel up,it is hanging by the cable and will bounce around if there is any wave action from boat traffic.
I would think that if a 25 foot motorhead came by with a large wake the keel cable and winch have to carry the load in a wake like that so I am of the keel down club at all times except at the ramp or when necessary for shallow water. If you trailer your boat leave the keel up after on the trailer and drive a short distance and watch how the keel moves in your review mirror, it will swing around very easily from side to side hanging from the cable.
Just my thought.
BJW
The leading edge of the keel is reduced in the up position but that does not seem to offset the fact that keel up,it is hanging by the cable and will bounce around if there is any wave action from boat traffic.
I would think that if a 25 foot motorhead came by with a large wake the keel cable and winch have to carry the load in a wake like that so I am of the keel down club at all times except at the ramp or when necessary for shallow water. If you trailer your boat leave the keel up after on the trailer and drive a short distance and watch how the keel moves in your review mirror, it will swing around very easily from side to side hanging from the cable.
Just my thought.
BJW
I guess that my (new) view on "keel up" is don't do it, or at least be very very careful of the conditions and local wind variability. A family launched a 22' swing keel boat here a few weeks ago, keel up. Light winds. Except here, nothing is stable. A big gust came up 'outta nowhere' and they capsized and sank. Thankfully, nobody hurt.
The local marina owner said "it could have happened to anyone".
The only time I have done it is after launch just like they did. I won't do it again, at least not here. And, yes, I know, keel up motoring is done a lot.
OC
The local marina owner said "it could have happened to anyone".
The only time I have done it is after launch just like they did. I won't do it again, at least not here. And, yes, I know, keel up motoring is done a lot.
OC
Up for trailering
A swing keel was designed for trailering. it’s shape and size was design for sailing and boat stability. Altering that design is when shit happens.
A swing keel was designed for trailering. it’s shape and size was design for sailing and boat stability. Altering that design is when shit happens.
I only raise the keel in shallows, I don't like the way she rocks and rolls and slides around with it up. Not sure if it makes much difference in terms of speed or fuel economy because I've never had to motor for any distance over about a mile. The keel lowered definitely keeps things quiter when anchored.
Oldcat, did the 22' that sank have sails up?
Oldcat, did the 22' that sank have sails up?
Nope, no sails up when it capsized. I will see if I can get more details later this week, or this weekend.
OC.
This past weekend I motored out of the harbor and into the bay, having to pass through a section that I would describe as two jetties lined with large rocks on either side. On the way out a large, 30’ motorboat, came into the jetties creating a large wake. My keel was up and I took the wakes at about the 11 o’clock position on the bow. It really through me about and caused me a lot of concern. I realized that if my keel was down maybe I would have handle the stability a little better. Reading the recent posting I will always have the keel down. My question is what would be the best way to take on this kind of wake from the point of speed while motoring, is slower better and position of the wake to the bow. Any thoughts, thanks.
I would just make sure I was motoring at least fast enough to keep the boat pointing in the direction I wanted, if you lose steerage you could get in trouble, and yes, keel down definitely. I have crossed wakes deep enough to "air out" the prop even with the extra long shaft, in which case I wouldn't want to be winding the motor out. In any case, I'm not sure if you could motor a 22 fast enough to do more than keep ample forward motion and steerage.
Gettin' technical!
I'll go out on a limb and say that the drag created by a retracted keel could exceed that of an extended one! In aviation, a long, slim, wing is more efficient (same lift at less drag) than a short, wide, one (called a long-chord wing). That's why sailplanes have very long, slim, wings. The longer a fluid (air or water) rides along a surface, the more drag is created. So when you extend your keel, the water rides across its shorter dimension; crank it against the hull and water travels across its full length. Approximately the same surface area is exposed each time, but the direction of contact is changed.
Additionally, there is a 3" hollow area in the bottom of the hull into which the keel retracts. When the keel is extended, this area is relatively free of obstructions to impede the water from travelling across it. Fold the keel up, and you create turbulence as the water is now forced through smaller openings between the hull and either side of the keel.
If anyone has access to a water tunnel (yep, it's a word, I looked it up!
) you can check the numbers and let us know. But I'm going with it!
Keep the keel down until you hit mud!
I'll go out on a limb and say that the drag created by a retracted keel could exceed that of an extended one! In aviation, a long, slim, wing is more efficient (same lift at less drag) than a short, wide, one (called a long-chord wing). That's why sailplanes have very long, slim, wings. The longer a fluid (air or water) rides along a surface, the more drag is created. So when you extend your keel, the water rides across its shorter dimension; crank it against the hull and water travels across its full length. Approximately the same surface area is exposed each time, but the direction of contact is changed.
Additionally, there is a 3" hollow area in the bottom of the hull into which the keel retracts. When the keel is extended, this area is relatively free of obstructions to impede the water from travelling across it. Fold the keel up, and you create turbulence as the water is now forced through smaller openings between the hull and either side of the keel.
If anyone has access to a water tunnel (yep, it's a word, I looked it up!
) you can check the numbers and let us know. But I'm going with it!Keep the keel down until you hit mud!
last night I was coming back into moorage on Lake Washington, I was heading straight into a 6-8 knot wind, motoring with my Sailmaster 6 my knot meter read 5.1 knots with the keel down, and the same speed with the keel up. this was at close to full throttle.
however, with a the same engine and different prop, smaller and more pitch, I have noticed about a .2 knot speed difference (faster) with the keel up compared to down.
Paul
however, with a the same engine and different prop, smaller and more pitch, I have noticed about a .2 knot speed difference (faster) with the keel up compared to down.
Paul
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