What to build centerboard out of?

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Nov 9, 2009
10
Irwin 25 Ormond Beach, FL
Hi there,

I just bought an Irwin 25 and I need to construct a new centerboard for it. I've got documents talking all about the dimensions (width is omitted for some reason) and talks about delrin rod configuration and how to run the line to the centerboard winch... But nothing really talks about what kind of material I should make the centerboard out of. And if the centerboard should be weighted or not.

Can anyone clue me in on what to build a new centerboard out of for my 1970 Irwin 25?

Also, the centerboard winch is missing. If anyone has any information about the centerboard winch I would appreciate that info too.

Thanks in advance.. If there is some visual aids you can link to, that would be sweet.
 

spuki

.
Jun 7, 2004
20
Irwin 10-4 Sanford, FL
We recently owned sailboat with a centerboard made out of 3/8 inch steel plate, but I don't recommend it unless you know the weight can be supported properly at the pivot pin. We have owned an Irwin 10/4 since 2001. From what I can tell the centerboards are made similar to rudders. The drawing for the Irwin 23 centerboard shows a thickness of 1 inch. Just thick enough for the groove that the cable rides in. If you don't want to build one out of plywood, glass and resin, lexan should work well. It is very strong, and can take some bending, as well. As long as it fits into the centerboard trunk in the raised position, it should be fine. You can always laminate thinner pieces together to get the thickness needed for the cable if you cannot get a sheet thick enough. If you do that, you will probably need to reinforce the lamination with an even distribution of bronze screws (counter sunk). I don't know what you would use for an adhesive, maybe some type of resin. This may end up being a bit heavier than a resin centerboard, but within a tolerable range. I would not add weights. If you found that a weight was needed, you would probably need to attach it the leadiing edge. Lexan will not float up, but a centerboard constructed more like a surfboard might. Hope this helps.
 
Nov 9, 2009
10
Irwin 25 Ormond Beach, FL
We recently owned sailboat with a centerboard made out of 3/8 inch steel plate, but I don't recommend it unless you know the weight can be supported properly at the pivot pin. We have owned an Irwin 10/4 since 2001. From what I can tell the centerboards are made similar to rudders. The drawing for the Irwin 23 centerboard shows a thickness of 1 inch. Just thick enough for the groove that the cable rides in. If you don't want to build one out of plywood, glass and resin, lexan should work well. It is very strong, and can take some bending, as well. As long as it fits into the centerboard trunk in the raised position, it should be fine. You can always laminate thinner pieces together to get the thickness needed for the cable if you cannot get a sheet thick enough. If you do that, you will probably need to reinforce the lamination with an even distribution of bronze screws (counter sunk). I don't know what you would use for an adhesive, maybe some type of resin. This may end up being a bit heavier than a resin centerboard, but within a tolerable range. I would not add weights. If you found that a weight was needed, you would probably need to attach it the leadiing edge. Lexan will not float up, but a centerboard constructed more like a surfboard might. Hope this helps.

This is great help, thank you.

I think after looking around on the internet some more and reading this and other posts that I'm going to go with plywood, lead, and epoxy. Still trying to understand how the pennant connects to the board and how the groove for the cable to ride in is best handled but I guess I'll just epoxy the pennant in place and grind the groove shape the best I can perhaps epoxy some tight glass weave in the groove for it to ride against.
 
1

10/4 parts

irwin 10/4 parts

I am dismantling a 1975 10/4. I don't have the centerboard itself, but I have all of the other parts to it. Including the winch assembly, cable, and dell-rod. I also have some detailed diagrams of the set-up. You can reach me at binder72@verizon.net Thanks Matt
Hi there,

I just bought an Irwin 25 and I need to construct a new centerboard for it. I've got documents talking all about the dimensions (width is omitted for some reason) and talks about delrin rod configuration and how to run the line to the centerboard winch... But nothing really talks about what kind of material I should make the centerboard out of. And if the centerboard should be weighted or not.

Can anyone clue me in on what to build a new centerboard out of for my 1970 Irwin 25?

Also, the centerboard winch is missing. If anyone has any information about the centerboard winch I would appreciate that info too.

Thanks in advance.. If there is some visual aids you can link to, that would be sweet.
 
P

Pater

.25 inch stainless is recommended. Mine is quarter inch thick bronze. They're good ballast, and can take groundings better than a wood board.
 
Nov 9, 2009
10
Irwin 25 Ormond Beach, FL
Plywood centerboard, nope.

Just an update,

I ended up making one out of 3/4" marine plywood with a bunch of 1" lead discs for weight and the whole thing was wrapped in glass and resin to 1" thick. it was a work of art and worked wonderfully for abut three trips when it broke off at in-line with the centerboard trunk.

It wasn't cheap to make. glass and resin was very expensive for this project.

I've been sailing without a centerboard all year.... Going to try again when it gets really cold. I'll haul it out and try something else this winter I bought a centerboard for another boat that I'm going to modify to fit my irwin. It's goign to be 8 inches too short but for $100 it's worth trying I think. It cost $200 in resin and parts to make the plywood one.
 

spuki

.
Jun 7, 2004
20
Irwin 10-4 Sanford, FL
Have you tried joining the Yahoo group for Irwin sailboats? http://groups.yahoo.com/group/irwinsailboats
You should join and ask some questions there. My Irwin does not have a centerboard. One of our smaller sailboats had a centerboard made of a steel plate, but it was not an Irwin. Could be that the plywood CB's have steel reinforcement similar to rudders. Don't know for sure.
 
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