STEP DOWN KEEL = MORE HEADROOM

[zimco]

http://www.sailboatlistings.com/view/21392

THE AMERICAN MARINER 24 IS QUITE SIMILAR TO THE CP23 IN DIMENSIONS, SHOAL DRAFT AND SAIL AREA.

THE MARINER HAS 5' 10" OF HEADROOM - DUE TO A STEP DOWN KEEL.  THE VOLUME OF BALLAST IN THE KEEL WAS REDUCED BY USING
ENCAPSULATED LEAD  INSTEAD OF THE CONCRETE AND LEAD MIX THAT COMPAC USES. 

YOU CAN SEE A PHOTO OF THE MARINER STEPDOWN KEEL AT :

http://www.sailboatlistings.com/view/21392

BE NICE TO HAVE A STEP DOWN KEEL IN OUR CP 23.


============

THE AMERICAN MARINER DOES JUST THAT .  ITS DIMENSIONS ARE ALMOST IDENTICAL TO THE CP23,

EXCEPT IT HAS 5' 10" OF HEADROOM!



L.O.A........ 24.0'
L.W.L........ 22.0'
Beam....... 7' 11 3/4"
Draft......... 28'
Sail Area:

Main..... 110 sq. ft.
Jib........ 140 sq. ft.
Genoa.. 150 sq. ft.


Rated Sail Area.. 250 sq. ft.
Hull........ Fiberglass
Spars........... Aluminum
Ballast........... 1200 lbs.
Displacement 4600 lbs.
Headroom..... 5' 10"
Berths............ 5
Auxillary:

Gas..... OMC
Diesel.. Yanmar
H.P. 15


Designer Arthur S. Henry

[Bob23]

   I wonder why the displacement is so much more yet the ballast is less. I believe this type of keel is called a box keel. The boat I saw (can't remember what it was) had a box keel but in reality there was only room to stand in a very small area.
   Very interesting but I doubt we could obtain standing headroom. I'll wait for someone else to modify thier 23!
bob23

[millsy]

I initially thought about "stepping things down" when I replaced the concrete with lead/batteries in my 23.  Working on the inside of the boat was certainly alot easier when I could stand up inside the keel cavity (with full standing headroom).  I think that this would work using lead only down low- not standing headroom but quite a bit more- but I elected to go with the original sole height in order to get the clearance I needed for the batts.

As built, I don't think that the skin thickness is enough down in the keel to support lead alone, and since you would not be able to install floors down there to stiffen it up (if you want to increase headroom) you would have to increase the thickness overall.  I thickened mine by about 3X and ran this up into the turn of the bilge.  Using the sandwich core might accomplish the same thing.

Regards,
Chris
Dolce C-23

[zimco]

 
ANY PHOTOS OF YOUR PROJECT?

HOW MUCH WORK TO REMOVE THE CONCRETE?

LON
PRUDENCE  PC23

===========

I initially thought about "stepping things down" when I replaced the concrete with lead/batteries in my 23.  Working on the inside of the boat was certainly alot easier when I could stand up inside the keel cavity (with full standing headroom).  I think that this would work using lead only down low- not standing headroom but quite a bit more- but I elected to go with the original sole height in order to get the clearance I needed for the batts.

As built, I don't think that the skin thickness is enough down in the keel to support lead alone, and since you would not be able to install floors down there to stiffen it up (if you want to increase headroom) you would have to increase the thickness overall.  I thickened mine by about 3X and ran this up into the turn of the bilge.  Using the sandwich core might accomplish the same thing.

Regards,
Chris
Dolce C-23
[/quote]

[millsy]

This is how I removed the lead


A problem:


Dry fitting the lead at the lower end of the keel cavity after repairs



Battery compartment under construction


New bulkheads, stringers and floors


Completed batt compartment


Interior shots

[newt]

Wow. Great concept but the work just makes me hurt. I have thought about a cast iron keel under the current one. It would be easy to make in my metal work class.- I would bolt it up and add about 6 inches to the depth.

[millsy]

My displacement is the same as yours.  I removed 1130 lbs of concrete (I weighed everything as I dumped it overboard) and replaced it with the equivalent in lead & batteries.  The difference, I suppose, is that the lead is down low in the keel- so the righting moment is probably slightly different.  But as far as the cast iron extension goes,  I say go for it!  No more need to worry about grounding on rock ledges!

BTW the caption for the first photo in my earlier post should have said "how I removed the concrete", but I'm sure you figured that out.

Regards,

[newt]

thanks for the instruction Chris, its got my mind aworking. How does it point?

[Bob23]

Interesting, Chris:
   What is your actual headroom now?
bob23

[millsy]

Newt, I have never had the occasion to compare upwind sailing with another 23.  I have an older set of sails, which might cancel out any benefit in having the weight lower down in the keel.  In heavier air I lead the sheet of the working jib through a fairlead on the forward end of the cockpit coaming, inside the rigging (these fairleads were there when I got the boat and I am glad I reinstalled them).  I think this helps in pointing higher and helps balance the helm.  I also have a foiled rudder.

Bob, the headroom is the same as it was before, it's just that now I have batteries (6 AGM's) mounted below the cabin sole.  I have another 2 AGM's below the cockpit, and use these (4 batteries each connected in series to make 2- 24VDC battery banks) to run a Torqeedo Cruise 2 -, about a 6HP equivalent OB.

[brackish]

Chris that is one super nice restoration job with a high tech twist.  Have you had enough time with the electric to give us a report about how it is working out?  Maybe start a new thread in the lounge.

[millsy]

Should the new thread be in the Boat and Hardware Modification or Lounge do you think?

[brackish]

Should the new thread be in the Boat and Hardware Modification or Lounge do you think?

Probably B &HM for future reference and archiving