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DragonPup1

Centerboard vs full length keel

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Greetings.  I am a newbie to this site, and a novice boat builder/sailer.  But having built the first of my intended three boats (the very weekender that is both praised and dismissed here) I am now ready to build what will become the tender for my final boat.  I hope to begin work on an Atkins schooner within two years.  My project for the winter is to build her tender, and the B&B Spindrift sounds like it would fit the bill.  I an just not a fan of a centerboard.  Has anyone messed about with a full length keel for the Spindrift similar to what the weekender sports?  How would she perform under sail or using oars?  Thanks for any insight you might have collectively.  I live in Nebraska, where the wind does come whipping off the prairie at a pretty good blow from time to time, but we don't have big enough water to allow much in the way of waves, at least not like the Big Blue Wet Thing.

 

Bill

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A full length keel is an option, but not one that will perform as well as others. The only reason this type of keel was employed, was to hold up the rest of the boat's parts. With modern materials and methods, this has long been unnecessary. A fin keel would be the best performance choice, though draft would be a consideration. Next on the list would also be a fin keel, but of lower aspect ratio, to address the draft issue. It wouldn't do quite as well as the deeper fin, but still pretty good, though a fixed draft issue will still exist. This is why retractable appendages, in some form, are often used in small craft. These types of boats, by their very nature are used in shallow water, where running aground or up onto a beach if desired, is a real likelihood. This isn't easily possible with a fixed single appendage, so some use twin fins (bilge keels), which allows the boat to take to ground bolt upright. These styles of appendages are common in areas with wide tidal swings, understandably. They still are draft restricted, but less so then the first two options listed. Last on the list is a full length keel, like that seen on a Weekender (tongue in cheek). A very shallow keel like this isn't very effective at much and the boat still flops over onto it's chine when run aground. This type of keel resists turning, so maneuverability is limited, it's draft is still fixed., quite poor windward ability and leeward skid is pronounced. None of these attributes are especially desirable, particularly in small craft and especially in places you're not familiar with (like that on a cruise). These and a few other reasons are why you see small craft with retractable appendages. From a bang for the buck (and weight) view point, they're difficult to argue against.

 

I'd recommend building some sailing experience before considering designing  a new appendage for a Spindrift. As you might expect, it's size and placement would be critical to performance and some additional structure, will be necessary to handle the increased loads, it'll impose on the boat and the rig. I would think a 12" deep appendage could be arranged, that wouldn't put much strain on the hull, yet keep the draft minimal. You'll likely loose several degrees of pointing ability and the same in tacking angles. She'll skid off a fair bit more and performance would suffer, but for a tender, how much sailing will you actually do.

 

Most tenders are powered, to remove the fuss of getting from the mothership to shore or a return trip with a few cases of beer, so a powerboat, without a daggerboard case, can prove a handy thing and why most are arranged this way. The ideal tender will be light, so it can be easily manhandled and hoisted to deck or davit, can carry a notable load, in various sea states and can be towed safely. Though sailing tenders can do these things, not as well as powered tenders. A real good tender is a lost art, but once you've owned one, you never go back to a small sailboat, pretending to be a tender, fixed appendage or not.

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I use a Spindrift as a tender and I find it meets all of the important criteria for one.

 

1. light weight (easy to carry and even lift on board)

2. good capacity (people and/or gear)

3. sails well (I very often sail in from my anchorage to the dighy dock, it is a classy thing to do)

4. easy to beach (a full keel boat is not)

5. tows very well (I doubt a full keel dinghy is)

6. stows on deck relatively easily (mine is a nesting version)

7. motors well (build a false dagger board/case plug)

8. rows well (this is why I never carry a motor for it)

 

BTW, it has a dagger board, not a center board.  Both are similar shape and location, but operate very differently.  A dagger board uses a smaller trunk (case).  This matters in a small boat with limited space.  It is less convenient as is slides up and out and can't be retracted under sail with out being in the way of a tack.  There are times I wish it had a center board, but over all I think Graham made the best choice.

 

I don't recommend trying to "fix" Graham's design, it ain't broken.

 

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Gentlemen:

 

Thanks for your insight.  And yes, I do plan to sail my boat until she becomes a tender.  Probably still then, too.  Wish I was coming to the mess-about.  It would be a good time to check out what options there are out there.

 

Bill

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Dave's post said everything that needs to be said about the Spindrift  as a tender.  I cannot fathom how one could find a long shallow keel to be a better choice for a small boat than a daggerboard.  I have never had a long shallow keel but have sailed them and seen many others and never want to get any closer to one.  Even though the DB does have its disadvantages, the advantages for a small sailboat/tender far outweigh them.

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This is an old post, but I wanted to add my "two bit's worth ".

To start I am not a proponent of either dagger boards or center boards. They tend to jam or get filled with sediment whenever a boat is beached.

My preference for beachable sailboats is bilge keels. These have a long tradition in Europe, especially in England, but for some reason in disfavor here in the US. I won'the go into the arguments pro and con since these discussions on the Web on this are already quite extensive, especially on its sailing characteristics.

Here in the US, Phil Bolger seems to have been the only proponent of bilge keels.

I favor this design because:

1. It simplifies hull construction in small boats (no need to worry about the torque on the box creating leaks)

2.It allows for easy beaching and sailing in shallow waters

3. Bilge keels that are about 1/2 the length of the bottom do not have to be very deep. My little logo shows the 21 ft Sharpie I just finished. The bilge keels on it are only 9 inches deep and 10 ft long but their cross section is equal to that of the 3.5 x 6 ft centerboard in the original design.

4. With the tiller hanging off the stern it turns easily and does not fall off the wind when tacking.

Tom

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