Centreboard Water Spouts

[Peter Cockerton]

During the recent sailing in Weymouth with the heavy swell the amount of water coming through the centreboard slot was quite significant. Until now i had only experienced water spouts when the boat reached around six knots.

I did fit the draught excluders to the top of the case to harness the spouts which in truth worked quite well but removed them to regain our emergency "comfort break facility".

I read somewhere on the forum about fitting a copper plate in the centreboard slot in front of the centreboard itself. This is have done using some thin but strong plastic material (see photograph) i will report back on the results.

[James Bennett]

Hi Peter
what I have done with our boat is to fit a 3mm sheet of materail called Ertalon between the stainless steel rubbing strakes. Ertalon is used as a bearing material and is available in sheet or tubualr form. If I did not have access to this material I would consider using polycarbonate or similar high strength plastic. The photo below shows what was done. I am on a mark II version with an even smaller hole for the echo sounder transducer to work through. The Ertalon is glued in place with Sikaflex. I have seen speeds of 5-9 knots on my boat and high waves and this has done the trick.
For the comfort break we carry a fur rimmed plastic bucket!

[Graham W]

For the comfort break we carry a fur rimmed plastic bucket!

James,

Still on the topic of water spouts, I can't quite envisage how or why your bucket is fur-rimmed.  Does it have to be from a specific furred aquatic mammal (eg sea otter, platypus, beaver) or will any species (mink, sable, Lumholtz's tree-kangaroo) do?

A hand bailer is used on Turaco. It's never actually been used for bailing.

[Peter Cockerton]

Hi Peter
what I have done with our boat is to fit a 3mm sheet of materail called Ertalon between the stainless steel rubbing strakes. Ertalon is used as a bearing material and is available in sheet or tubualr form. If I did not have access to this material I would consider using polycarbonate or similar high strength plastic. The photo below shows what was done. I am on a mark II version with an even smaller hole for the echo sounder transducer to work through. The Ertalon is glued in place with Sikaflex. I have seen speeds of 5-9 knots on my boat and high waves and this has done the trick.
For the comfort break we carry a fur rimmed plastic bucket!

James
 
The material i used is from a car boot liner, so I'm guesssing it is polycarbonate, i was hoping the transducer will work through the sheet so no hole required, we shall see next time it,s on the water. Must admit yours looks a neater job but i didn't want to lift the rails off the bonding. I used tiger seal a sealer and adhesive to bond the sheet to the rails and as you can see stainless penny washers.

Great to hear the sheet idea works, Graham the bailer will definitely be considered in the future, in that swell the one arm press up required for the centreboard facility was hard work although a salt water built in bidet was very refreshing.

Peter

[Graham W]

I think this stuff is similar (or even identical) to Ertalon http://www.ebay.co.uk/itm/NYLON-66-Nat-Sheet-200-x-300mm-in-2-3-4-5-or-6mm-thick-/360913837971?pt=LH_DefaultDomain_3&var=&hash=item5408241f93

[Peter Cockerton]

Graham

Well spotted, i was just starting to look myself for the material. I want to try and reduce the other problem which i found annoying, "Rudder Play. iwill raise a seperate post.

Peter Cockerton

[Graham W]

Peter,

See http://www.swallowyachtsassociation.org/smf/index.php/topic,329.0.html

[James Bennett]

Peter/Graham

To reply on the main theme, the Ertalon sheet I have used is 3mm  thick, which is the same thickness as the stainless steel keel runners. The arrangement of my centreboard area was such that the Ertalon sheet could be glued direclty to the boats GRP structure without disturbing the stainless keel bands. Take a look at the attached picture and you can see that there are white flat areas of GRP in way of the centre board casing and under the red trailer roller to glue the Ertalon to. I did reinforce the Ertalon edges where the transducer lies by gluing additional flat bits of Ertalon to the main part so that the whole assembley was stiffer in this unsupported area.
To ensure the Ertalon was well bonded I removed the red trailer roller and used my car jack and a piece of wood to create a gentle but firm pressure on the Ertalon.
In theory I could remount my echo sounder and bond it to the back of the Ertalon sheet, so there is no aperture at all and therefore an even smoother fairing piece.

With regards to the material used on the bucket rim, I fear that this strategic matter cannot be disclosed. Its a pretty competative arena out here in Western Aus'. I have Chris R in Gryphon (BR20) and others in our fleet of small boats watching my every move! Suffice to say that the rim complies with RSPCA and all rare and endangered species regulations. Most importantly the crew is happy with the arrangement.

[Peter Cockerton]

James

Thanks for clarification and it's clear now on the installation method used. Will try my mod out hopefully this week and if i get the boat above 6 knts hopefully the water spouts will not occur, the spouts from the boat slamming into swells is another matter as i mainly sail reservoirs due to my home location so it may be a time before that can be trialled.

 My trailer design does not have the roller positioned close to the centreboard case, I'm hoping that the area of the plate will never touch a roller as the boat should lift from the swinging arm onto the side rollers before getting to that area.
Will update when i can.

Thanks

Peter

[Peter Cockerton]

James

The centreboard  axle pin is fixed i see with hex grub screws  through the stainless bands, interesting because i see your hull has a groove worn area where the pin was either pushed into place after the bands were fitted or where a dislodged pin wore away the gelcoat. Originally on UK hulls the pin was held in place by "bookends" of raised fibreglass which failed on several boats. The fibreglass bookends are now upgraded to stainless ones bolted through the hull.

Are the grub screws a mod to your boat.

Another UK mod was to change the stainless band fixing screws (one each side of the centreboard axle) with nuts and bolts through the hull into the tank. This was to ensure that the stainless bands could not lift from the hull and allow the axle pin to move. If your grub screws hold the centreboard axle with just pressure fix it may be worth checking this.

Here is the link to the original post

http://www.swallowyachtsassociation.org/smf/index.php/topic,336.0.html

Peter Cockerton

[James Bennett]

Hi Peter
good pick up! I noticed that after I had posted the picture of my centre board area that the photograph was labelled "grub screws in keel band" which is a bit of a give away.
This is a modification that I made after almost losing the centreboard pin a couple of times after some heavy air sailing. After some correspondence with Denman Marine and others on the quiet I decided to install the grub screws myself as I thought that they presented the best idea at the time.
I was offered hull mounted stainless steel pin stoppers but did not like the idea of an external stainless fitting that could catch debris or be damaged if the boat was sitting on the beach.
I practised the job on the work bench and proved to myself that my rudimentary skills and tools were sufficient to do the job. However lying under the boat and working a thread over head into the stainless steel keel bands just about finished me off. One grub would have been sufficient, however one of the threads that I made was a bit dodgy so being a glutten for punishment, I added a better and more secure second grub screw (practise makes [almost] perfect)
I am very pleased with the result, the centre board pin has not moved since.

[Peter Cockerton]

James

The grub screws through the steel bands looked to me to be the best solution at the time and was mentioned on the forum. As i didn't want to attempt to drill and tap stainless from under the trailer the problem was resolved with the stainless tabs (bookends) bolted through the hull into the tank, so well done mate.

You may want to look at the other suggestion made on the forum and now adopted on all new builds i understand, that is to improve the band fastening to the boat either side of the centreboard pin by removing the small screws, drilling holes right through into the tank and installing stainless nuts, washers and bolts. This prevents the steel bands lifting from the boat where pressure is applied by the centreboard and pin. In your case the grub screws rely heavily on the bands not moving and if they did the grub screws would not stop the pin from moving.

Peter Cockerton

[Graham W]

Here's a picture of an altogether larger water spout, which appeared out in the bay within a couple of hours of our arrival in Corfu.  It lasted a few minutes, died away and then tried to reform. I reckon the diameter of the spray ring at its base was at least 50m.

[Peter Cockerton]

James

Sailed the other day conditions which didn't really test the plate mod but the transducer will not ping through the polycarbonate sheet so cutout now made to try the next time I'm out. It may work if no gap present between transducer and sheet but this is not the case with my arrangement.

Peter