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CP23 Trim

Started by brackish, November 12, 2009, 12:55:49 PM

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brackish

With four light folks in the cockpit, weighing a max of 600 lbs., a bone dry bilge, port cockpit locker very lightly loaded with an aluminum anchor and rode very little else, starboard cockpit locker having two batteries, charger, switch and a shore power cord., 104 lb four stroke motor, about two gallons of gas in the tank, no ice chest or any other heavy items aft of center, I noticed while under power at about 30% throttle, water just forward of the fuel locker area.  Not a lot but enough to indicate the scuppers were trimmed down and water was coming in.

Motor is set at minimum angle to transom.  Motor mount is set with one space left to be at minimum.  Motor seems perpendicular to the world at rest.

My question for other 23 owners is this typical?  I may try to close the angle to transom with that last setting on the mount to get the tail up and the nose down but I'm afraid it might take it too far and I'll plow a bit.

Frank

Craig Weis

#1
You bet cha! At speed our sail boat hulls squat down by the stern. Bow high. We don't really have a 'planing hull' but a positive displacement hull, not meant for motor boat speed. I believe this squat is countered by the 'sail up' mode as this pushes from just behind the bow, wow, wow and not the stern. I guess if you kick the motor a bit 'under' the stern you may 'bow down' a bit. But why bother?

On a windy day I can get 5.4~to 6.1 knots on the sail power and on a calm day about 5.4 knots on just the 5 hp 2 cycle...so I'm thinking my sails make 5 hp?

But actually the more weight astern when under sail the slower you'll go. You want weight up front, where the broadest part of the hull is to speed you along. So I'm told. I have no idea why.

My Neighbor Tim Graul is a marine architect and he sails a cat boat. Says for every 75 ponds force on the sail about 15 pounds end up at the keel pushing the hull forward. Tim designed the Dennis L Sullivan, State of Wisconsin's schooner.
skip.

edbuchanan

Hi Frank,

My boat is usually loaded quite heavily for cruising.  For example, forward of the mast I have a full water tank, two steel anchors, 75 pounds of chain, etcetera.  With my family of three in the cockpit it scarcely makes any difference in trim.  When the water tank is running low, the boat does not feel right.  The scupper drains are almost always out of the water and it is very rare to take water in the cockpit.

On the negative side, Molly used to semi-plane in a good blow, and now that is impossible with her load.

Ernie (Molly 23/II, 1984)

kchunk

Frank, we've gotten water up the scuppers under power. I'll usually throttle back as I'm seldom in a hurry. Never really thought much about nor tried to do more about it other than slow down.

--Greg

nies

Greg, with a cockpit grate the water" back flowing" under power is below the grate, thus no wet feet......Phil

kchunk

Quote from: nies on November 12, 2009, 08:44:43 PM
Greg, with a cockpit grate the water" back flowing" under power is below the grate, thus no wet feet......Phil

Thanks Phil, but sailing where I usually sail, wet feet isn't normally an issue. Two possible issues I can think of: a) I don't want all the extra weight of the water aboard and 2) If I recall (and I don't really recall this very well), but I think the scuppers run through plumbing between the underside of the cockpit floor and the transom. If something happened to this plumbing I hate the thought of pumping the basement of my boat full of sea water. Nothing I'd lose sleep over, but something to think about I suppose.

--Greg

Bob23

Greg:
   I agree. I thought about replacing that hard pipe with some flexible hose to take any movement between hull and cockpit. Better yet, woud be to redo the drains straight through the transom at the floor level. 1 1/2 inches would be my minimum ID.
   I also get a bit 'o the briney in through the scuppers when loaded and motoring. If that's the worst habit my 23 has, so be it. She's really a well behaved lady.
Bob23

brackish

Thanks folks, looks like it is fairly normal.  I may try the last shaft angle adjustment on the mount but if that won't work won't worry about it.  I think some may have 2 cycle eights back there and are probably carrying 40 less lbs. at the end of the moment arm.  Weight times distance equals force... well you know...  I'll do a little weight distribution try to send some stuff forward to compensate, but for the most part will just relax when the little puddle sneaks out from under the fuel locker cover.

On the positive side, I did find a reasonably large cooler that will fit the reduced height of the 23/IV.  Yeti Sherpa 50 qt.  Not inexpensive, however, truly a lifetime, multiple day cooler.  I ordered one, they are being discontinued in favor of a line that will not fit my space, so I'm getting one while I can.

Frank 2.  (not to be confused with Frank 1, FO48 who is a year younger)

johnny b

Yes, I've had the same experience too when the boat is similarly loaded.  And I only have one battery, and a 65 pound engine.  If the scupper intakes are at or slightly below the waterline, a little water will flow in.

BobK

The water entering the rear scuppers has a lot to do with the displacement hull nearing or exceeding the hull speed.  As the boat reaches hull speed the bow is trying to lift over the bow wave that is formed, the center of the hull is in a trough  and the stern wave moves behind the stern of the boat.  Any increase in speed causes the bow to raise higher and the stern to sink lower.  This causes the scuppers that are normally dry to be under the water level allowing the water to enter the cockpit.
 

HideAway

The only time we get water through the scuppers is sailing hard on the wind with 20 degrees or more heeling.    I have an older 8hp 2cylce, six gallon tank, one battery and some lines in the hold.   I think you can buy a flapper valve that attaches over the scuppers on the transom.  Otherwise we try to keep the weight forward as well.   Matt
SV HideAway Compac 23 Hull #2
Largo, Florida
http://www.youtube.com/SVHideAway
http://svhideaway.blogspot.com/

Craig Weis

The standard scupper is 1-1/4" on the CP-19 with a flapper to limit [not stop] water from rolling in during a following sea or spirited sailing.
skip.

nies

The scupper with flapper only limits and does not stop the water, at least on my boat. Again skip is right....Phil