Sunday, March 11, 2018

Fixing a Lame Bowsprit

It's not that I work slowly, but often I make changes in small increments, careful to make certain each change and the entire project is optimized. This one took nearly 6 months to completion.

I didn't photograph the original mess of cracked welds and failed screw repairs. I just ground it all away.  The original fitting did not cradle the butt end of the bowsprit and did not extend completely to the end.

The Failure. The original hinge mechanism included an undersized butt cradle that ended up cracked on most F-24s. It was simply under-designed.Often the sprit was also dented. There was no line to hold it up, and sheets often snagged down low, around the jib furler.

The new aluminum cradle is both wider and built from heavier material. The plastic insert is curved to match the pole. These dimensions are approximate--you will need to measure your own.
This should be as strong as the pole. However, I always tension the up-haul snugly to carry the opposing load, should the bobstay be inadvertently over-tensioned.

Larger bolts (#10) were tapped into the side pieces. Additionally, the cradle is wider and reaches to the end of the pole.

Then there was the matter of articulation. The original design incorporated a fix bobstay and could only be folded or extended at dock, or by hooking your legs around the pulpit and reaching for a pelican hook at the waterline. Not fun under way in any weather. Some owners fitted a tackle using blocks, but the load is high and they're bond to catch junk. I also wanted more purchase, to reduce the load on the line clutch. Enter Low Friction Ring (LFR).

Fortunately Amsteel is super easy to splice. The yellow is a Dyneema Climbing sling. The safe working load of this tackle is about 3000 pounds, stronger than original.

I used rings from Antal, Ronstan, Harken, Nautos, Wichard, and Scheafer, all part of a Practical Sailor research project. Though I reported my favorites, they all work just fine. An up-haul was also added, not apart of the original design. This relieves the load from the butt cradle and keeps the reacher sheets from going under the pulpit where they can hang-up. It also secures the sprit against the pulpit when not in use (I wrapped a sort section of the pulpit with 3/16-inch line so that it would not bang when stowed). A lucky coincidence of geometry, the travel of the 4:1 down haul and the 2:1 up-haul are the same, making a continuous line a neat solution. Because Amsteel is slick, I covered (bury splices) the center section of the line with polyester cover so the clutches would hold properly.

A surplus Easy-Lock clutch is mounted to an aluminum plate (tapped), which is in turn mounted by bolts through the hull flange, neatly out from under foot. Another LWR keeps the line tail neat.



The final result is easy to use, and lighter and stronger than factory. The side stays are looking a little rusty, so they will be replaced with Amsteel soon as well.

How fast? Over windspeed on a reach. Mid-teens are common, though a little scary if it's gusty.

1 comment:

  1. Drew - I have the same issue with the butt cradles and wonder if you have dimensional drawings for the revised aluminum cradle? I would love to get it made by someone local here. Also - what size are the screws? Also - if it is easier, my email is devinvanzandt at gmail.com

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