modern high exit spinnaker tubes

[bill platt]

To fellow 505 sailors, I have a huge favor to ask, if possible can you provide feedback?

We are reconfiguring a Lindsay bag boat to be a bow launcher boat, and would like to survey the fleet about the arrangements that are out there for the tube. I made a 3D model of the 505 and have noticed that it seems like some or all of these newer boats have a tube that runs "uphill" going aft, and there are drain holes cut in the bow. Preliminary calcs seem to show about 15 kg of water would accumulate in the tube, after stuffing a wave. I am a bit concerned about that--or is this not an issue in practice? Our old boat has a traditional launcher tube which exits to a sock down low--so water always comes into the cockpit bilge very quickly.

Attached are two sketches, asking for dimensions if possible to obtain.

D=depth of opening at bow, from top of gunwale to bottom of mouth

Z=distance from lower edge of exit to inside of bottom at centerline at WT bhd

H=depth of tube at WT bhd

Y = width of tube at WT bhd

I had also considered making a round tube 20 cm in diameter but that may be more difficult to demould and fit to at the mouth.

A bit of history for this boat: it was originally a launcher boat, but in the early 80s timeframe was converted to a bag boat. She still has the original aft tack fitting and 165 mm diameter hole in the WT bhd (sealed off).  I have considered returning to the original idea, but with a larger diameter. However, all that extra spinnaker length in the bilge seems problematic and directly clashes with the shroud purchase rigging. Perhaps it really is easier to reconfigure the shroud rigging to suit the low exit, and make a longer sock? So far, a few sailors I have talked to, who have sailed big spinnakers with both arrangements have preferred the high exit.

Best regards,

Bill

[Blaine Pedlow]

Hi Bill,

These articles on the website (usa505.org > Library) might be relevant for you. Assume that you may have read these already, but just in case.

The tube has a flange and is sealed at the forward bulkhead. Historically, many boats had a mesh "sock" that then ran aft through a hole in the diagonal bulkhead, then was secured pulling it tight aft. When doused, the spinnaker would be in that sock, keeping it out of purchases. The helm (or perhaps the crew) douse the spinnaker via a block at the aft end of that sock.

Most modern boats have the tube exit high and do not use a sock. Crews douse the spinnaker by pulling aft on the retrieval line directly out of the tube. After doused, they toss the end of the spin with the retrieval patch up forward of the diagonal bulkhead and it stays up there.

The low exit tubes drain the water into the cockpit. High exit tubes have drain holes forward and drain any water over the side.

I think that you will also find lots of great photos on the internet of what these tubes / exits / dousing systems look like. Check out the Thompson Boatworks website for lots of images of boats that Craig has rigged. There also are lots of photos in the Class Library on the website.

Good luck! And ask more questions if you have them.

Blaine

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[Dustin Romey]

Bill,

Though it's been a few years, I've creweded extensively on both a Waterat bag boat converted to a side launcher (8012), and modern Rondars with the drain holes and an uphill tube, as well as some time on Waterats and Lindsays with the more traditional launcher set up you describe.

Practical experience is stuffing the bow is equally bad in all of them.  You either have to wait for it to drain out the bow, or out the bailers.  Neither is fast enough.

There are endless debates about the tack forward boats and the pros & cons.  I'd summarize it like this:

• They don't seem to be any faster upwind, though it seems easier for some drivers to get them in a groove at max speed.
• As a crew, the side launcher is absolutely fantastic if you're pulling the halyard/retrieval on the set and launch.  The more modern design has a much smaller mouth.  I understand there's been some fittings made to increase that by moving the jib tack up a couple of inches. But it's a big difference in how quickly you can pull it up/down.
• The side launcher is MUCH easier to get the spinnaker guy over the bow.  On that boat we always had an extendable tiller extension so I could steer from the wire while Henry played 12 meter bowman and cleared.  We got it down pretty well. And good team coordination minimizes it also.  But it was always easier to do.

All in all, I didn't think it made a ton of difference.  I thought the hull shape differences were much more noticable in how we sailed the boat.

If I were picking one to install, I'd be more likely to consider the side launcher.  I didn't take part in the installation, but understood it was relatively easy compared to the work necessary for a typical launcher install. Just plan on practicing keeping the kite flying through gybes in light-medium air to avoid running over the sheet or guy.

Dustin