Lapstraking the Haven 12 1/2

[thurman]

Joel White's Haven 12 1/2 is carvel planked. Has anyone ever heard of this boat being lapstraked instead of carvel planked?

[Danford C. Jennings]

thurman,

I certainly haven't. Why, are you thinking of doing one that is lapstraked? If you are, might I suggest that you take a black and white photo copy of her sail plan lines and drawing in the strakes as you envision? This will give you a fairly clear idea of what a lapstraked Haven would look like.

If you like the look, order the plans, redo the scantlings for the appropriate number of steam bent ribs and strakes, determine the adjusted displacement, recalculate the new center of effort, and make the proper adjustments from there. Oh, don't forget to redesign the keel, stem, transom, centerboard trunk and all the other smaller details like sheer clamps, deck beams, mast step, and etc. Hope this helps.

Dan

[Keith Wilson]

Oy, another version of "The sky will fall if you deviate from the Writ Of God as revealed through his representatives Nathaniel Herreshoff and Joel White". As you might guess, I don't have a lot of patience with this.

I've never seen a lapstrake 12-1/2, but IMHO it's not at all unreasonable. One might want to build a lapstrake Haven for any of several reasons:
- Lapstrake construction, whether traditional or glued plywood, stands wet-dry cycling much better than cavel planking.
- Some like the appearance of a lapstrake boat better.
- Some prefer this method of construction, or are just more familiar with it.
One of the reasons Joel White reworked the original Herreshoff 12-1/2 was to reduce the draft so that it could be put on a trailer without undue difficulty. The Haven 12-1/2 would make a decent trailer sailer (with a long trailer tongue), except for the fact that carvel planking has trouble with wet-dry cycling. Havens have been built cold-molded for this very reason, and lapstrake has some advantages over cold-molding.

I'm scarcely an expert, but I don't see anything in the design of the Haven that woul be terribly difficult to build lapstrake, particularly in glued plywood. There's a little hollow at the garboards, but nothing too troublesome. I see no reason whatever that you'd have to make major design changes unless they're directly related to the planking. Displacement and center of effort certainly won't change significantly. The rest of the boat, like the keel, centerboard trunk, deck beams, etc can be left just about exactly as drawn, or modified for more "modern" construction in order to better stay tight when trailering; your call. With reasonable care and a certain amount of familiarity with other similar-sized boats built lapstrake, I don't think it would be at all difficult to make the conversion, although a 12-1/2 isn't a simple boat to build no matter how you do it. In fact, I think a glued-lapstrake Haven 12-1/2 would be a very nice boat.



[This message has been edited by Keith Wilson (edited 04-17-2001).]

[Danford C. Jennings]

Mr. Wilson,

You misinterperted my response to thurman's question totally.

I responded to what I thought was a serious question in like manner, with what I believe to be valid points to considered. There are many advantages to lapstrake construction particularly when strength to weight ratios are considered. Even minor changes to the center of effort can have significant impact on the handling characteristics of a boat powered by a sail. The higher the wind speed the, the more these characteristics will be magnified.

I do not know thurman's level of skill and made no assumptions, as you have.

Dan

[Keith Wilson]

Oops - I appear to have detected sarcasm where none was intended. I have disputed with enough Herreshoff True Believers that I mistook the intent of your post. Sincere apologies.

Seriously, though, the change in displacement and underwater shape from going from smooth-skin to lapstrake planking is so small that it will be entirely obscured by other things; position and weight of the crew, sail trim, CB position, etc. Basically, it will be lost in the noise, assuming that one gets the shape reasomably close to the original. My point, despite the misunderstanding, was that the conversion might be relatively straightforward, and wouldn't require major changes

[Danford C. Jennings]

thurman,

Let me expand just a tad on my first post.

I recall "WoodenBoat" initial article in "Designs" concening the Haven 12 1/2. Having kept a copy of the line drawings, I sketched in the strakes last night after I posted. I found your question intriqing, as I am particularly fond of lapstrake constrution. IMHO, it looks "sweet".

The points that I brought up are valid. Any changes is design could be very simple ones. I did not imply that it needed to be redesigned from the keel up. It could very well be that all that needs needs to be redesigned on the keel and stem is the rabbet, I don't know as I don't have the actual construction plans.

I do believe that a lapstraked Haven would raise the center of effort and could possibly be compensated for by in using a heavier center board, additional ballast, or both to maintain the sail plan.

I'm sure that someone has had the same thoughts as you. Hell, there could be some that have been built and the owners are spending more time enjoying their use more than surfing the net.

My point was and is, draw in the strakes to see if you like the look, if you do make the commitment to build her, and get the plans knowing what could be involved.

Mr. Wilson correctly points out that building the Haven is not easy. There have been a couple of books written on just the construction alone. FWIW.

Dan

[Danford C. Jennings]

Keith,

Apology accepted. I am new to this forum and do not know anyone yet.

I just came here the other night asking for assistance and found some of the posts to be interesting. In return for the help I recieved, I thought some reciprocation would only be proper.

Dan

[Danford C. Jennings]

Thurman,

A few other thoughts popped up, before I head out to the shop.

My initail instinct in regards to a lapstraked Haven is that because of the hydro dynamics of a lapped strake hull, I suspect that on downwind and broad reaches, speed would be improved over a carvel planked hull depending on layout.

I recall a design by Weston Farmer that involved a light displacement hull using "reversed" lapstrakes, below the water line, that improved hull speed.

Dano

[ahp]

Originally posted by thurman:
Joel White's Haven 12 1/2 is carvel planked. Has anyone ever heard of this boat being lapstraked instead of carvel planked?

Thurman,

In 1959 I had built a "Spartan" class keel sailboat in England. She was very similar to a Folkboat, and designed by Alan Buchanan. I clearly recall that I had the choice of carvel or lapstrake construction. The basic hull was priced then at 700 pounds for lapstrake and 900 for carvel. I chose carvel.

The Haven has hull form similar to the Spartan. I don't see why you couldn't do it either way.

Art Pierson