Author Topic: Shoal vs Deep Draft  (Read 2923 times)

Bevan Daverne

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Shoal vs Deep Draft
« on: May 01, 2009, 11:40:57 PM »
Hi Everyone,

I am a new member on this forum (was not on the old one) and am currently looking for a CSY 44 W/O that would be a project boat.  I have just missed out on a deep keel version (my preference - but bidding went too high) and so am currently considering another shoal draft model.  Theoretically, with less depth of a keel, there is decreased righting moment and a compromise on sailing characteristics.  I would like to hear your opinions on whether this fits with your experiences.  When the keels on these boats are cut,  the loss of concrete may not have the same effect on the righting moment as the concrete density is so much less than lead (144 lbs per cubic ft vs 690 lbs per cubic ft).  As to the windward sailing performance, in your experience, do the shoal drafts perform that much differently than the deeper keeled versions.

Unfortunately, living in Canada does not afford us much opportunity to cruise the Bahamas or Caribbean, so a shallower draft is not on our "must have" list.

On a related note, Mars Keel has done refits on "cut keels" where they provide a pair of split torpedo bulbs to bolt on the sides of your existing keel to return a little more ballast without increasing draft.  I'm not sure this would have any effect on windward sailing characteristics, but it does beg the question if anyone knows of a situation where a CSY had any keel depth added back on?

I look forward to any opinions on this topic - based on the quality of posts on the old forum this looks like an excellent and Knowledgeable group.

Bevan Daverne
« Last Edit: January 27, 2017, 11:16:04 PM by Soggy Geek »

Soggy Paws

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Shoal vs Deep Draft
« Reply #1 on: May 02, 2009, 07:14:23 AM »
Bevan,

For starters if you have time do a search on the Topica site on keel length.  There has been some posts on this subject in the past.  The designer, Peter Schmitt told me personally a year ago that there is very little difference in upwind performance between the two keels and no stability problems with the short keel version.  I suspect it is more like 5 degrees of leeway more for the short keel. 

We are about to depart on an airplane, now so I have little time.  There are other advantages/disadvantages which I can post to you later.  We are commencing a circumnavigation now with a short keel tall rig and I have sailed our boat around the Carib and up and down the Keys many times.  We don't have any problem with our boat's upwind ability especially since we have a well tuned rig and new sails.  I believe that those two things will make more difference in upwind ability than the 18" of keel length.  Of more concern is where you may cruise in the future and whether or not you can get into the places you want to.

I have considereed "capping the keel" with a plate on the bottom to direct the water flow along the keel rather than have it fall off the bottom and cause turbulance drag but haven't gotten around to that yet.  20 years ago I talked to Ted Brewer about this and he seemed to think that it would be a worthwhile project on a new shallow draft boat build.  I think that it would help upwind performance some on a CSY.

The shallow draft models from the factory were supposed to have 2000# added to their keels to offset the weight of the deeper keels.  I haven't noticed any stability problem with our boat, but if you were concerned you could always add lead, and you would want to do this if you cut off a keel.  More on stability, etc later.

Dave
« Last Edit: January 27, 2017, 11:16:54 PM by Soggy Geek »
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Bevan Daverne

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Shoal vs Deep Draft
« Reply #2 on: May 03, 2009, 01:51:08 PM »
Hi Dave,

Thanks for the quick response.  I had not realized that the factory produced a shoal dreft version.  In my reading to date, it had appeared that all boats were produced with the deeper keel and then some of them were modified.

I appreciate your comments on windward performance as well.  Do you know how to tell if a particular boat is factory shoal or has had it's keel cut?

Bevan
« Last Edit: January 27, 2017, 11:17:54 PM by Soggy Geek »

RosalieAnn

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Shoal vs Deep Draft
« Reply #3 on: May 05, 2009, 04:59:49 PM »
Almost all the WTs came with shoal draft and tall mast.  There were one or two that did not, but I can't open the database that I have ATM to look and see which they are.  (Computer problems)

I have not seen a boat that I knew had the keel cut although I do know some of them have - I just haven't seen them in person.  Somewhere I have a list of which ones of the Pilot Houses came shoal and which came deep draft.  Ron may have that.  I think Tempest had hers cut off. 

Ours is a shoal draft which I think came that way from the factory.  She came up to the Annapolis Boat show after she was built and has always been in the Chesapeake.  The boat that was originally named Owl of Athene (and I think the lastest name is Song Bird) was also a Chesapeake boat originally and is shoal draft.  The Chesapeake and the Bahamas are two places where the shoal draft might be preferred.  That is not to say that there are not some deep draft boats there.  Magic Kingdom does quite well in the Chesapeake with deep draft.

I think owners could specify if they ordered direct from the factory, so if you come across a boat that is still with the original owner and is shoal draft I think you could be pretty sure that it was built that way.  Actually, I think it is pretty rare that a shoal draft boat is one that had the keel cut off.  It doesn't happen that often.  I would imagine that it is a major PITA to do.
« Last Edit: January 27, 2017, 11:18:59 PM by Soggy Geek »

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Shoal vs Deep Draft
« Reply #4 on: May 08, 2009, 02:44:11 PM »
Bevan,

Re cut keels: according to the CSY manual the concrete was first poured into the empty keel and then covered by an upper fiberglass keel bottom 18" up.  So, once you identify where the upper keel bottom is, it is relatively easy to cut the fiberglass just below this around the outer perimeter of the keel with a circular saw.  Since there is no mechanical connection of the concrete to the fiberglass the lower portion of the keel will then drop off.  From there it is a simple matter to dress up the edges and paint after applying a barrier coat. 

I have heard of several cut keels and seen one done by a friend in Key West.  It was done in a day by just blocking the boat up and cutting a half inch or so below the upper fiberglass bottom.  Since the concrete is not physically attached to the fiberglass, when the outer fiberglass is cut the fiberglass encased concrete keel falls off.  All cut keels that I know of were done to 44 walkovers.  If you are interested in looking at a cut off keel, I believe that Steve Silverman has one.

To answer your question how to identify a cut keel, I would look for a keel bottom with sharp edges and maybe no gelcoat on the bottom.  Factory keel bottoms have a thick layer of gel coat and are fairly flat, while a cut keel bottom might show raw fiberglas, no gel coat and maybe an imbedded concrete pattern.  Also, the loss of keel weight might have been offset by a knowledgeable owner with additional lead ballast placed in the bilges-something you could see.

If you are still looking for a project boat you might consider, Pacifico now in the Rio Dulce for sale at $55K.  It was a bit rough and needed work, but was being used for cruising in the Carib.  We were next to them on the Rio at a marina for a few months a year ago.  What boat are you looking at now?

Dave
« Last Edit: January 27, 2017, 11:19:34 PM by Soggy Geek »
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Ron Sheridan

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Shoal vs Deep Draft
« Reply #5 on: May 08, 2009, 09:03:19 PM »
IF: you want DEEP DRAFT or SHOAL DRAFT info that has been available, try reading this link and/ OR, report  your thoughts: http://csysailboats.blogspot.com/search/label/Keel%20Cutting

Ron
« Last Edit: November 06, 2017, 09:59:33 AM by Soggy Geek »

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« Reply #6 on: May 09, 2009, 01:23:05 AM »
Ron,

Thanks for the input.    This has been a long standing subject of discussion.  I had not seen your info on keels before.  Good to have it referenced in this thread.  In any case, this is another good example of why we need to get data like this all in one place under the same topic.

We all know that the keel does 3 major things for a boat underway: improves stability by adding weight below the center of gravity, provides lift because of its foil shape and improves lateral resistance because of its surface area.  Those are all pluses for a deep keel.  The question is how much of a plus.  According to Peter Schmitt, our designer, when I asked him that question directly, not much.  With a little time someone could probably come up with the calculations to analyze the differences.  And maybe there is someone reading this forum that can provide an accurate analysis based on actual experience with both hulls.  But even that would be hard to evaluate because of the differences between any two like boats' sails, rig tuning, bottom condition, etc.   

On the negative side are the significant issues of 19" of increased draft (as you know a real problem getting into the Rio Dulce, and elsewhere), increased wetted surface area and reduced slippage down a large storm wave.  Regarding the 6'-6" initial draft and more like 6'-10" or better in cruising trim, there are many places in the southern US, Bahamas, the Carib and even Ecuador that are a big problem for a boat with that kind of draft.

So there you have it again, tradeoffs and compromises.  I still like my tall rig shoal draft (now more like 5'-3" in cruising trim) for what we are doing.  My gut feeling is that there isn't that much difference in performance or stability between the two keels to make me look for one or the other if I was buying a boat.  For us the difference in draft is the real issue.

Maybe there are others who will want to weigh in on this to help Bevan make an informed purchase.

Dave
« Last Edit: November 06, 2017, 10:25:59 AM by Soggy Geek »
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Bevan Daverne

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Shoal vs Deep Draft
« Reply #7 on: May 09, 2009, 01:27:18 PM »
Hi Everyone,

Thanks for all the comments - the boat that I had been considering definitely has had it's keel cut:
http://www.yachtworld.com/boats/1978/Csy-Walkover-1965322/St.-Thomas/Virgin-Islands-%28US%29

Apparently, (from what I have been reading) the loss in ballast is about 2000 pounds.  I believe CSY designed the keels this way for this very purpose.  My only thought is that the loss of 2000 lbs (at the lowest point in the keel no less) must have some effect.

This boat needs considerable cosmetic work as well system upgrades - I am still sorting through my options on this one.  I would also like to keep it on the west coast, so another issue is one winter's storage on western Mexico. Unfortunately, there are very few of these on the west coast, but after a lot of research, the CSY has definitely become my first choice and so I am looking for a way to make it work.

Bevan
« Last Edit: November 06, 2017, 10:02:49 AM by Soggy Geek »

RosalieAnn

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« Reply #8 on: May 17, 2009, 09:06:44 AM »
Quote from: Bevan Daverne
My Apologies - I have posted the wrong link - that one is to a beautiful boat , but out of my price range atm.

This is the one with the cut keel that needs work:
http://www.yachtworld.com/boats/1978/Csy-Walkover-1965322/St.-Thomas/Virgin-Islands-%28US%29

Bevan

How do you know that this boat has a cut keel?  It is a shoal draft, but (as we have been discussing) not all shoal drafts are cut.
« Last Edit: November 06, 2017, 10:05:15 AM by Soggy Geek »

RosalieAnn

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« Reply #9 on: May 17, 2009, 09:09:51 AM »
  All cut keels that I know of were done to 44 walkovers.  If you are interested in looking at a cut off keel, I believe that Steve Silverman has one.

I think Dave K. said that he knew of one of the smaller ones that was done, and also I do know that a pilot house was done.  But I think Steve has a WT (originally named Shepard's Rest).  He wanted a deep draft and was considering trying to put the keel back on.
« Last Edit: November 06, 2017, 10:06:05 AM by Soggy Geek »

Bevan Daverne

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Shoal vs Deep Draft
« Reply #10 on: May 17, 2009, 02:23:54 PM »
Hi all,

I should probably be more careful with my terminology.  Saying the keel is "cut" makes it sound like some kind of butcher job and, from what I have read, the design intention from factory was to make it simple to allow this modification to a shoal draft on the W/O models to allow options for owners.  As many of you have pointed out, the keel construction was set up to make this factory intended option an easy one to follow through with.  Thank you for all the replies on sailing characteristics - it would seem that CSY's perfom very similarly regardless of keel configuration.  I think the comments on the condition of the sails make a lot of sense.  BTW, the reason I knew the boat in question had its keel modified was that the broker had been provided that information from the original owner (who had made the modification as a better fit for sailing in the Caribean islands)

Bevan
« Last Edit: November 06, 2017, 10:06:45 AM by Soggy Geek »

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Shoal vs Deep Draft
« Reply #11 on: May 19, 2009, 10:25:47 AM »
Rosalie and Bevan,

Steve does in fact have a WT with shoal draft.  He has acquired the cut off keel itself to possibly reinstall.  I'm working on trying to talk him out of it.

Dave
« Last Edit: November 06, 2017, 10:07:14 AM by Soggy Geek »
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Soggy Geek

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Shoal vs Deep Draft
« Reply #12 on: June 13, 2009, 11:14:46 AM »
Bevan (and all)

Found this page on Ed Marrill's site, with a scanned copy of the original discussion from CSY on the deep or shallow draft.

Thought you'd be interested (thanks Ed!!)

Deep or Shallow?
« Last Edit: November 06, 2017, 10:11:59 AM by Soggy Geek »
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Shoal vs Deep Draft
« Reply #13 on: June 13, 2009, 05:52:36 PM »
Also a company who's business is to work on keels and stability (thanks to Ron Sheridan's original post on Topica in 2007).

https://marskeel.com/production/repair-modifications/draft-reductions/

Mars Keel's business IS keels.

BTW, I am a shoal draft fan (started cruising in 1974 on a multihull, and being able to anchor in 3' deep water opens up SO many anchoring possibilities). 

Soggy Paws' 5'4" (+-) draft is DEEP for me!

We have the shoal draft/tall rig combination, and it's "good enough" for world cruising.  Having a near 7-foot (by the time you load it down) draft excludes you from so many anchorages, and that can be dangerous in itself.  (Just trying to point out that the 'stability' issue isn't the only issue)
« Last Edit: November 06, 2017, 10:29:19 AM by Soggy Geek »
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Re: Shoal vs Deep Draft
« Reply #14 on: November 06, 2017, 10:19:35 AM »
To put the final response on this.  Since we left Florida in 2007, we cruised almost 40,000 miles across the Pacific in all kinds of weather and sailing conditions.  We were fortunate in choosing our weather conditions (thanks to modern forecasting and modern communications technology), and never had to sail in over 40 knots, and then only for a few hours.  We NEVER felt unsafe in our shoal draft / tall mast CSY 44.

We sold Soggy Paws in 2016, and she was subsequently sailed from the Philippines to Western Australia, where she now resides.

If you plan to cruise in areas where draft is an issue (inland river waters, Bahamas, etc), you really should consider the shoal draft.  If you plan to cruise in areas where draft is not an issue, and heavy weather is normal, the full keel might be a better choice.

Here is a video taken of a CSY 44 Walkthrough (formerly Tackless II, now Kenebec), shoal draft, tall mast, under sail in winds gusting to 40 knots.

https://www.youtube.com/watch?v=-mcFgd8qEyA&feature=youtu.be

Sherry
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