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Admiral Hornblower

Fireball centreboard case support replacement

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DSCN3346.JPG.b44f0e656c148164950a2ac01883020e.JPG

The two struts on either side of the centerboard case have failed, are in need of replacement before we can sail it again.

Any suggestions for a fix, preferably from wood? 

thanks, Amn H

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 plywood pads unders struts have delaminated and one the struts just completely fell off when I was messing with control systems. At the point where they attached to the centerboard case I think the fiberglass holding them in place just failed.

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Bugger

Just a thought... can the new ones be moved forward to give more room for the crew?

Triangles of marine grade plywood with the centre cut out, pads to spread the load tapered at edges to avoid hard spots, sealed and glue into place

Others will have other ideas that will be more specific for a Fireball

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Post some photos of what went wrong.  Help is on the way with probably a few different opinions.     

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I think normally you want the support of the CB case fairly inline with the CB pivot pin (bolt), as this is the area that gets the most pressure when the CB is in its normal down position.  It probably means you want to keep the new support structure (however you decide to do it) in about the same place as it is now.  While giving the crew more room to move, supporting the CB case is more important.  The crew needs to adapt in this case, NOT the boat.

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2 minutes ago, koolkat505 said:

I think normally you want the support of the CB case fairly inline with the CB pivot pin (bolt), as this is the area that gets the most pressure when the CB is in its normal down position.  It probably means you want to keep the new support structure (however you decide to do it) in about the same place as it is now.  While giving the crew more room to move, supporting the CB case is more important.  The crew needs to adapt in this case, NOT the boat.

I agree.

It looks like there is a vertical support on the CB case where the strut currently is.  Has this been added along with the existing struts?

Where is the pivot pin? Photo?

 

 

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I Used a plywood bulkhead extending from the case to the side tank, the timber on the front top edge of the bulkhead was about 25x25 and this extended through the side tank out to the side stay reinforcing. The jib fairlead cars were mounted on the aft side of the top of this bulkhead.

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I'd cut some almost triangles of marine ply and epoxy in with a decent fillet. Remove the lower corner where the case/floor meet so that we can move about on the floor.

Cheap, quick and easy.

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23 hours ago, Ned said:

Post some photos of what went wrong.  Help is on the way with probably a few different opinions.     

next time I am down where the boat is stored I'll get some pics

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23 hours ago, Rushman said:

I agree.

It looks like there is a vertical support on the CB case where the strut currently is.  Has this been added along with the existing struts?

Where is the pivot pin? Photo?

 

 

the vertical support was added along with the existing struts, I believe

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17 hours ago, European Bloke said:

I'd cut some almost triangles of marine ply and epoxy in with a decent fillet. Remove the lower corner where the case/floor meet so that we can move about on the floor.

Cheap, quick and easy.

would that be sufficiently strong for, say, sailing in 25+ kts?

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1 hour ago, Admiral Hornblower said:

next time I am down where the boat is stored I'll get some pics

That's important.  In the meantime look at details in photos of other boats online, both Fireballs and other dinghies.  Your objective is to transfer the load from the head of the centerboard into the hull.  And transfer the load of your crew landing on top of the centerboard case in a crash from the trapeze into the hull.  Make it solid side to side and distribute that load through the structure to avoid point loading and hard spots where you have a stiff repair on a flexible material.  

The options could range from rebonding what you have, to making something new that is simple, to making something new and spiffy.  

Anyway post pics especially of where the patches popped off and let's see if the collective can get you sorted and back on the water.  

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54 minutes ago, Admiral Hornblower said:

would that be sufficiently strong for, say, sailing in 25+ kts?

No. Fillets suck. They ALWAYS break. Stiffness without strength will take the load and then fail. You have to tape the fillets.

 

ideas.PNG

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That looks like pre 1970s construction 

The trunk is much more well supported on modern Fireballs. 
 

there is a ton of information available from the association and the current sailors. 
please look in that direction 

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9 hours ago, Gouvernail said:

That looks like pre 1970s construction 

The trunk is much more well supported on modern Fireballs. 
 

there is a ton of information available from the association and the current sailors. 
please look in that direction 

IMG_7048.JPG

I like the placement of the centerboard support here, Except isn't that to far forward?

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9 hours ago, fastyacht said:

No. Fillets suck. They ALWAYS break. Stiffness without strength will take the load and then fail. You have to tape the fillets.

 

ideas.PNG

thanks, I'll consider that. how thick should the plywood be?

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55 minutes ago, Admiral Hornblower said:

thanks, I'll consider that. how thick should the plywood be?

6 mm

However, if the simple thwart going from top of trunk to top of side tank is acceptable, it is nuch easier and lighter.

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Not a pre 70s boat with a number over ten thousand. Looks like pin is forward of the old strut. Easy fix with new supports and good for as much wind as you can handle. 

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I think you would want to support it at 30% chord rather than at the pivot bolt. That's where the max. force would be.  I know on my 505 the pivot bolt is at least 6" ahead of the 30% chord and there is almost zero pressure there.

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33 minutes ago, dburchfiel said:

I think you would want to support it at 30% chord rather than at the pivot bolt. That's where the max. force would be.  I know on my 505 the pivot bolt is at least 6" ahead of the 30% chord and there is almost zero pressure there.

It looks like there's a lot of stiffness in the top of that case though (and a thwart further aft). Could you get away with siting the new support/thwart a bit further forward to make the crew's life a bit easier, and rely on the case capping to distribute the load from the board into the two thwarts? Siting a thwart slightly further forward also gives the opportunity to tie into the (hopefully stiff/strong) structure that keeps the shroud plates in the right place.

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It has been a while, but with my size 12 feet I would remember an obstacle up front - and I don’t. I would have busted those supports you have in your boat - or broke my ankle. There has to be a more elegant solution. Fastyacht’s looks pretty good. @GBRNoah might have an idea/photo.

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7 hours ago, Bill5 said:

It has been a while, but with my size 12 feet I would remember an obstacle up front - and I don’t. I would have busted those supports you have in your boat - or broke my ankle. There has to be a more elegant solution. Fastyacht’s looks pretty good. @GBRNoah might have an idea/photo.

I agree. I think I am going to go with fastyachts idea.

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Well, as you asked, this is the way Severn built them in the early 90's. OK - it's a foam / glass hull and ply deks, tanks & bulkheads, but the principle still applies. The fwd web goes all the way to the hull and effectively closed the stress triangle formed by the shroud base when rig tension is applied. The jib bars are only ther efor in/out adjustment and are secured to apad on the side  tank. Fairly sure they don't go as far as the hull.

I don't think you need tape if you have a decent epoxy / resin mix with fibres in it for strength and some colloidal silica to help it stay where you put it before it goes off. 2nd pic shows my repair to the side tank / floor join where it had started to fail. I cleared out the old (small) fillet, drilled some 1/8" holes about 1 or 2" apart then injected a warmed resin mix using a syringe, so it could spread along the join inside the tank. Masking tape over the cockpit / side tank join while that cured, then added the fillet. Shame the colur didn't match but she was already nearly 20 years old then! Difficult part was getting the floor horizontal fore & aft to make sure the mix went where I wanted it.

 

IMG_1545.JPG

IMG_1549.JPG

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3 hours ago, GBRNoah said:

Well, as you asked, this is the way Severn built them in the early 90's. OK - it's a foam / glass hull and ply deks, tanks & bulkheads, but the principle still applies. The fwd web goes all the way to the hull and effectively closed the stress triangle formed by the shroud base when rig tension is applied. The jib bars are only ther efor in/out adjustment and are secured to apad on the side  tank. Fairly sure they don't go as far as the hull.

I don't think you need tape if you have a decent epoxy / resin mix with fibres in it for strength and some colloidal silica to help it stay where you put it before it goes off. 2nd pic shows my repair to the side tank / floor join where it had started to fail. I cleared out the old (small) fillet, drilled some 1/8" holes about 1 or 2" apart then injected a warmed resin mix using a syringe, so it could spread along the join inside the tank. Masking tape over the cockpit / side tank join while that cured, then added the fillet. Shame the colur didn't match but she was already nearly 20 years old then! Difficult part was getting the floor horizontal fore & aft to make sure the mix went where I wanted it.

 

IMG_1545.JPG

IMG_1549.JPG

Thanks!

Is that your Fireball? If it is, I'm green with jealousy.<_< How many fireballs do you have?

btw, is that a downhaul you have rigged for your rudder?

 

 

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7 hours ago, GBRNoah said:

Well, as you asked, this is the way Severn built them in the early 90's. OK - it's a foam / glass hull and ply deks, tanks & bulkheads, but the principle still applies. The fwd web goes all the way to the hull and effectively closed the stress triangle formed by the shroud base when rig tension is applied. The jib bars are only ther efor in/out adjustment and are secured to apad on the side  tank. Fairly sure they don't go as far as the hull.

I don't think you need tape if you have a decent epoxy / resin mix with fibres in it for strength and some colloidal silica to help it stay where you put it before it goes off. 2nd pic shows my repair to the side tank / floor join where it had started to fail. I cleared out the old (small) fillet, drilled some 1/8" holes about 1 or 2" apart then injected a warmed resin mix using a syringe, so it could spread along the join inside the tank. Masking tape over the cockpit / side tank join while that cured, then added the fillet. Shame the colur didn't match but she was already nearly 20 years old then! Difficult part was getting the floor horizontal fore & aft to make sure the mix went where I wanted it.

 

IMG_1545.JPG

IMG_1549.JPG

If you compare these photos to the layout of an epoxy Winder you could easily come up with the best position for the bulkhead so it supports the sideways loading on the top of the case as well as provides a place to position the jib cars. They should not get in the crews way at all, every single competitive Fireball in the world has similar reinforcements.

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14 minutes ago, Major Tom said:

If you compare these photos to the layout of an epoxy Winder you could easily come up with the best position for the bulkhead so it supports the sideways loading on the top of the case as well as provides a place to position the jib cars. They should not get in the crews way at all, every single competitive Fireball in the world has similar reinforcements.

For sure. The bars in OP’s initial photo look farther back.

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3 hours ago, Admiral Hornblower said:

Thanks!

Is that your Fireball? If it is, I'm green with jealousy.<_< How many fireballs do you have?

btw, is that a downhaul you have rigged for your rudder?

 

 

I have just the one! The pic is of the first ‘ball I owned. Bought in late 2004, sold in late 2009 to fund the Winder purchase. Severn did build a nice looking ship, and well put together. 
Yes, it’s a downhaul I rigged for the rudder. Those cast IYE stocks (rudder head in US-speak?) are a bit rubbish and I was never happy with the sacrificial pin idea. It does need a 2:1 purchase and a break-out cleat to work properly. The odd rope routing just kept the line off the aft deck.

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19 minutes ago, Bill5 said:

For sure. The bars in OP’s initial photo look farther back.

The jib bars on the Severn boats didn’t have the range of adjustment that the Winder’s do (or most of them anyway), but it is simple and it is a lot cheaper. The theory is that as the car moves outboard the sheeting angle changes to open the leech and tighten the foot. Not sure it ever worked quite right, but the sails I was using were not necessarily cut with that in mind. The clew position needs to reflect the way the sheeting position is arranged.

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I meant to write earlier but sneaking a few comments on phone at break at work is clumsy.

Note that the tubular Dog's Breakfast that broke is clearly put there out of frustration with some problem of the past. Was the trunk leaking? Board panting? What? That was a bad "fix." The doubler on the skin was better than nothing but a clumsy and in effective way to brace the trunk.

Since you are committed to doing something, do it right. Do take the time to follow what Tom says about Winders, and crew position, and putting a good stiff load path to the rig. Get it right and it will be a much better result. The same work either way. Some sanding, some cutting, some fitting and some glueing.

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5 hours ago, Major Tom said:

If you compare these photos to the layout of an epoxy Winder you could easily come up with the best position for the bulkhead so it supports the sideways loading on the top of the case as well as provides a place to position the jib cars. They should not get in the crews way at all, every single competitive Fireball in the world has similar reinforcements.

Now that is a gorgeous boat.

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7 hours ago, dburchfiel said:

Now that is a gorgeous boat.

She certainly was. 14268. Built in 1991 by Severn Sailboats. Bought by me in a state of mild neglect in 2004. Refurb was mainly sanding & varnishing, and sorting the string. Sold to France in 2009 and not heard of since, barring one photo I found of her on a quiet lake or river a year or so later.

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6 hours ago, GBRNoah said:

She certainly was. 14268. Built in 1991 by Severn Sailboats. Bought by me in a state of mild neglect in 2004. Refurb was mainly sanding & varnishing, and sorting the string. Sold to France in 2009 and not heard of since, barring one photo I found of her on a quiet lake or river a year or so later.

The first boat I built was 14299. Sailed a Severn on Lake Bala in Whales in 1993 while on the start of a 3 month Campervan holiday through Europe. I remember it being a well constructed boat and everything seemed to work well.

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Think you’re going to have problems fitting/raising the centreboard 

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18 minutes ago, GBR2083 said:

Think you’re going to have problems fitting/raising the centreboard 

Nothing a saw will not fix :ph34r:

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Cut that piece away from the centerboard slot, tidy up the exposed ends and:

The boat’s sail number shall be cut approximately 2mm deep into the thwart in figures which are not less than 25mm in height. 

 

 

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4 hours ago, Bill5 said:

Cut that piece away from the centerboard slot, tidy up the exposed ends and:

The boat’s sail number shall be cut approximately 2mm deep into the thwart in figures which are not less than 25mm in height. 

 

 

Crap. Well, what tool can I use to cut those numbers?

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18 hours ago, GBR2083 said:

Think you’re going to have problems fitting/raising the centreboard 

Actually, we found that the centerboard can be in its full up position without hitting the thwart.

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47 minutes ago, Admiral Hornblower said:

Actually, we found that the centerboard can be in its full up position without hitting the thwart.

You must have a batshit crazy board. Is the bolt in?

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10 hours ago, European Bloke said:

You must have a batshit crazy board. Is the bolt in?

Doesn't surprise me that much; I don't know about the Fireball class specifically, but dinghy centreboards have become a lot higher-aspect over the last few decades, where class rules permit.

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12 hours ago, Admiral Hornblower said:

Actually, we found that the centerboard can be in its full up position without hitting the thwart.

How about the fully down position?

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Posted (edited)
14 hours ago, Admiral Hornblower said:

Crap. Well, what tool can I use to cut those numbers?

Draw out the numbers (maybe use a template?) and then use either a very sharp, very small chisel, or a 3mm drill. Fill the engraving with coloured epoxy for contrast and revarnish. I’m not sure anyone would be harsh enough to throw you out for missing numbers though. And you can omit the country code - just the numbers are needed.

14268 number detail.jpg

Edited by GBRNoah
pic added
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I have never seen a Fireball thwart flush over the centerboard box opening. I see the original thwart in post 1 is two pieces, as are those shown in 16 or 17. 45 above goes over, but there is a spacer between the centerboard box and the thwart, with a couple inches of board sticking up. Yet in post 1 it does appear the centerboard does just squeak under where the one piece thwart would go across. This certainly does lead one to believe the board is an interesting shape. 

Concerning the carved numbers, no one will care but it is one of those rules that bows to tradition. Growing up with Fireballs, to me it finishes the boat off. 

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I thought there was a minimum height for the top of the centreboard case. Turns out I was wrong. There isn’t. 

9.12 Centreboard Case
No part of the centreboard case or the centreline structure above the cockpit sole shall exceed 320mm in width, except for struts, knees or strain members, the total of which shall not exceed three on each side of the centreboard case. The fore and aft dimension of any strut, knee or strain member shall not exceed 50mm when viewed in plan.
The slot shall not exceed 30mm in width. The sides of the slot opening in the bottom of the boat may have a radius. Slot closure strips are permitted.


9.13 Centreboard Pivot
The pivot shall be centred 70mm±7mm above the outside of the centre bottom panel, and 2698mm ± 26mm from the aft transom measured along the bottom panel. The pivot shall be fitted passing through the centreboard pivot hole.

The thwart must be excluded from the ‘strut, knee or strain member’ list above.

Maybe Admiral’s boat has an unusually high c/b case...

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I think I'm just going to cut the area of the thwart over the CB case opening. I think it is more aesthetically pleasing  that way. It also seems to be the thing to do on Fireballs.

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Just now, Admiral Hornblower said:

It also seems to be the thing to do on Fireballs.

That's because most Fireball centerboards protrude well above the CB case when raided, so it is a necessity. But I agree it does look sharper.

@GBRNoah I am trying to do the math of a high CB case. Would the front of the board need to be longer? Or the "nose"? I am just imagining it being lowered all the way, and if the case was higher the board would disappear down the slot a few inches. Does that happen Admiral? Can you post a pic of the board before you put it back in? I am curious....

 

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2 hours ago, GBRNoah said:

I thought there was a minimum height for the top of the centreboard case. Turns out I was wrong. There isn’t. 

9.12 Centreboard Case
No part of the centreboard case or the centreline structure above the cockpit sole shall exceed 320mm in width, except for struts, knees or strain members, the total of which shall not exceed three on each side of the centreboard case. The fore and aft dimension of any strut, knee or strain member shall not exceed 50mm when viewed in plan.
 

What are the thwart rules as there seems to be a bit of a contradiction here?

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40 minutes ago, Major Tom said:

What are the thwart rules as there seems to be a bit of a contradiction here?

"The height of the top of the thwart above the outside of the centre bottom panel, or its extended plane, shall nowhere be less than 256mm."

 

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1 minute ago, Bill5 said:

"The height of the top of the thwart above the outside of the centre bottom panel, or its extended plane, shall nowhere be less than 256mm."

 

More interested in the fore and aft dimensions of the centreboard case supports.

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4 minutes ago, Major Tom said:

More interested in the fore and aft dimensions of the centreboard case supports.

50mm as above. Are you considering the thwart to be a "strut, knee or strain member"?

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On 10/5/2020 at 1:04 PM, Bill5 said:

That's because most Fireball centerboards protrude well above the CB case when raided, so it is a necessity. But I agree it does look sharper.

@GBRNoah I am trying to do the math of a high CB case. Would the front of the board need to be longer? Or the "nose"? I am just imagining it being lowered all the way, and if the case was higher the board would disappear down the slot a few inches. Does that happen Admiral? Can you post a pic of the board before you put it back in? I am curious....

 

DSCN4056.thumb.JPG.06caa12fc7847b8a45f1cd77ee5af50a.JPGDSCN4058.thumb.JPG.7cf7d5987e543108fe2f22cbea1c7255.JPG

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I think we are all interested in the part that is missing from the photos, the top of the board and the handle.

The concern is, if the case is really high, when the board is fully down the top of the board will be below the horizontal lip of the casing and the handle will be taking all the load.

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On 10/5/2020 at 5:58 AM, GBRNoah said:

Draw out the numbers (maybe use a template?) and then use either a very sharp, very small chisel, or a 3mm drill. Fill the engraving with coloured epoxy for contrast and revarnish. I’m not sure anyone would be harsh enough to throw you out for missing numbers though. And you can omit the country code - just the numbers are needed.

14268 number detail.jpg

This of topic, but what are those circular through-deck fairleads you are using for the control lines on the CB cap?

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4 minutes ago, Admiral Hornblower said:

This of topic, but what are those circular through-deck fairleads you are using for the control lines on the CB cap?

They're just stainless lined thru deck bushes or bullseyes. https://www.sailboats.co.uk/allen-s-s-lined-through-deck-bush-id-6mm. Push fit (maybe aided by a little glue) into the timber c/b capping. 

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On 10/5/2020 at 6:04 PM, Bill5 said:

That's because most Fireball centerboards protrude well above the CB case when raided, so it is a necessity. But I agree it does look sharper.

@GBRNoah I am trying to do the math of a high CB case. Would the front of the board need to be longer? Or the "nose"? I am just imagining it being lowered all the way, and if the case was higher the board would disappear down the slot a few inches. Does that happen Admiral? Can you post a pic of the board before you put it back in? I am curious....

 

Not sure on the shape / size. I know they have to fit into a template for measurement (well, maybe not HAVE TO, but that's the way it's done at international championships). The rules don't appear to govern the size or shape of the head of the board. (See section 14.2 https://www.sailing.org/tools/documents/FIR2015CR230615-[18969].pdf). Most boats built since the late 80's (guessing), have a pair of cheek blocks mounted on the 'nose' and a rope arrangement for raising and lowering the board (except 14268 didn't :-( ). I'll see if I can dig out a photo from the current boat. 

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26 minutes ago, Admiral Hornblower said:

DSCN4083.thumb.JPG.adbfba7db6781e5a6eb2f2858dc521a7.JPG

I give up. Looks normal to me. 

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9 hours ago, Admiral Hornblower said:

Same kind of thing, yes. Bore might be a bit small though on that particular item. The Ronstan item shown is a 4mm equivalent. Mine were 6mm I think.

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On 10/9/2020 at 3:10 AM, GBRNoah said:

Same kind of thing, yes. Bore might be a bit small though on that particular item. The Ronstan item shown is a 4mm equivalent. Mine were 6mm I think.

would these work as well? https://www.westmarine.com/buy/ronstan--press-fit-deck-bushing-5-16-inside-diameter--P000283798?pCode=283806&amp;cm_mmc= 

 

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On 10/5/2020 at 5:51 PM, Admiral Hornblower said:

I think I'm just going to cut the area of the thwart over the CB case opening. I think it is more aesthetically pleasing  that way. It also seems to be the thing to do on Fireballs.

For goodness sake don't do that if you don't have to. It greatly reduces the strength. 

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