new bow sprit. Class legal?

Topics about Class Rules and the RRS.

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breeves
Posts: 7
Joined: Sun Sep 08, 2013 11:10 am

new bow sprit. Class legal?

Post by breeves »

new bow sprit arrived from Hall Spars today with a strop rather than u bolt. Is this class legal?
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Bengt J
Posts: 54
Joined: Tue Oct 25, 2016 2:36 pm

Re: new bow sprit. Class legal?

Post by Bengt J »

The Technical Committee is investigating and collecting data from boats with both new and old sprit design as well as US and EU built boats.
Bengt J
Posts: 54
Joined: Tue Oct 25, 2016 2:36 pm

Re: new bow sprit. Class legal?

Post by Bengt J »

The new outboard end cap design from Hall with a Spectra loop through the center is class legal.
Replacing the old end cap with the new design, as a reasonable cost to repair wobbly/worn U-bolts (kit will be available), is allowed.
Incorporating a block or low friction ring in any of the designs, to reduce friction on the tack line, is allowed.
What is NOT class legal is the approximately 2.5” of additional horizontal extension of the vertical bearing surface for the tack line this new design will result in.

In a sample of boats of various age, with the various end cap designs, all but one was found to extend the vertical bearing surface for the tack line up to 5 1/2 inches past the specification/class rule of maximum 66”.
In order to bring the class into compliance with this rule, the maximum extension should be measured and the rubber bumper preventing forward extension of the sprit moved accordingly. A second bumper may be added to the sprit or forward bulkhead. If a boat fails inspection before a regatta a temporary stopper line run parallel to the shock chord is allowed.

A pass/fail template will be made to help check the maximum extension of the sprit/tack-line. This tool may also be used at class events to check for compliance



For a printable drawing, download this pdf file.
J109 sprit.pdf
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Vento Solare
Posts: 393
Joined: Wed Dec 31, 1969 8:00 pm
Location: Newport, RI

Limiting Sprit Extension & Measurement Template Check

Post by Vento Solare »

Bengt Johansson brought one of the bow sprit measurement templates to Rhode Island so we could check some boats locally. I just had my sprit returned after it was sprayed with black Awlgrip and decided to show a method to limit excessive bow sprit extension. This was done at the dock with the bow accessible to make working easier.

1. The sprit was extended at maximum length
2. The template was used to check the extension. The template is placed on the outer load bearing surface (U-Bolt outer edge for original design, front edge of sprit for those with a low friction ring on a Dyneema loop, or front edge of Low friction ring if it is hard mounted). The aft end of the measurement template must reach the stem head fitting - if it does not, the sprit extension is out of spec too long. If you measure the distance from the end of the template to the stem head fitting, you may record this measurement and create a hard stop the same length.

Below is a simple hard stop that can be fabricated. I used a piece of 1/4" polypropylene that was sitting in the junk pile but you can also use a scrap piece of hardwood.

The restraining stop is fabricated from 1/4" polypropylene that is 1" wide. There is a 3/4" diameter hole drilled at one end that will keep the stop against the rubber bumper at the aft end of the sprit. The length is determined by setting the sprit to the specified extension, then measuring from the rubber bumper to the inside of the tube the bumper mates against.

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The stop is held in place with tape wrapped around the sprit, but could be held in place with adhesive.
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The restraining stop in position limiting the extension of the sprit. Note that the stop is mated with the aft surface of the white sleeve bearing.
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Bow sprit measurement template against the load bearing surface at the front of the sprit. This sprit configuration has an Antal ring bolted to the sprit, thus the forward edge of the ring is the load bearing surface.
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Bow sprit measurement template aft end showing proper measurement position on the stem head fitting.
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