Converting '73 Javelin to mid-boom rigging?

[RaleighRancher]

I've got a 1973 O'Day Javelin with the end of boom rigging as shown below. I'm thinking about converting to mid-boom so that the mainsheet isn't triangulated over the transom. (The goal is to keep my trolling motor from tangling in the mainsheet.)

I've looked at D&R's product page for Javelin lines & sail handling (DR Marine Product List), looks like the "Javelin Mid-Boom Mainsheet Complete w/Boom Block 3:1" is about 75% of what I need.

What should I be looking for to replace the original cam cleat and fairlead on the centerboard trunk? The current cam cleat & fairlead assembly only has a single block; not a fiddle and no becket.

Any drawbacks to this plan?

 

[Dave Groshong]

Can you show the cam on the centerboard trunk?

 

[RaleighRancher]

Can you show the cam on the centerboard trunk?

Not a great picture, but it's like the one here at the aft end of the CB trunk - just a single block and a pivoting cam cleat.

 

[Joe]

Moving to a mid boom system means you lose the purchase provided by the boom's leverage. Therefore you'll need to make that up by adding more power to the tackle system. Looking closely at your first picture, I think I see a becket on the existing mid boom block. All you really need to do is add a double block to the bottom part then. Anchor the sheet to the top block's becket, then down to the first sheave, back up to the boom, then down to the second sheave and exit to the swivel cam cleat. The result is a 3:1 mainsheet purchase. I think 3:1 is enough but you can always add more if you feel it's needed and your budget allows. Good luck, have fun.

 

[RaleighRancher]

Thanks. That's really what I needed - the logic to it. Could've worked it out myself but overexposure to the internet has retrained my brain to just go ask somebody smarter.

The upper block is a fiddle block, rather than a becket, but I can just do it in reverse. I'm not near my boat now, but I'm going to presume the lower block is removable from the bracket it shares with the cam cleat. Thus I will obtain a new block with a becket in hopes of installing it there.

 

[RaleighRancher]

I think I've got it sorted out except one thing. Looks like I need to completely replace the block and cam cleat on the centerboard trunk with a new fiddle block and cam cleat mounted to a new pad eye. (The existing single block is permanently fastened to to swivel assembly. I could take a hacksaw to it, but I hate mangling an otherwise perfectly good piece of hardware.)

Does anyone know what the swivel assembly is screwed into? Is there a backing plate with nuts, or is it just screwed directly into the FG?

 

[RaleighRancher]

Here's a better picture of the block/cam cleat/swivel assembly, scraped off the interwebs.

 

[Seaswood]

Once you mess with that unless you are sure how it is attached, I assume it works as shown?