chainplates

[sardinebreath]

[QUOTE=Jim Cate;1551163]

But, for many designs, having the chainplates outboard will have detrimental effects on windward performance, increase chafe issues, and look kinda agricultural (IMO).



Why windward? I would have thought it mostly impacts off wind sailing as the main will contact the shroud sooner.

[73Islander36]

sheeting angle

[Jim Cate]

[QUOTE=sardinebreath;1551782]

Originally Posted by Jim Cate

But, for many designs, having the chainplates outboard will have detrimental effects on windward performance, increase chafe issues, and look kinda agricultural (IMO).



Why windward? I would have thought it mostly impacts off wind sailing as the main will contact the shroud sooner.

G'Day S'Breath,

The loss of windward performance usually comes from having to sheet a genoa outside of the shrouds, and hence the minimum sheeting angle is greater with outboard shrouds.

Conversely, moving them outboard will not change the angular relationship of the mainsail and shrouds much at all, so no change in DW sailing. The contact spot where chafe occurs is moved a bit outboard, but this doesn't affect sailing performance.

Cheers,

Jim

[Fortytwo]

Removed the wood panelling. Removed the foam insulation behind the wood panelling. In the forward hanging locker I removed a shelf and in the head I cut away part of a shelf. Used a oscillating tool to cut away the glass over the chainplates. Used a grinder to cutoff the nuts on the inside that were seized (except for the one that fell off when I put a wrench on it). Hammered and punched out the bolts. Used a hydraulic jack, chain, metal bar and cribbing to pull the plates out through the toe rail. Used oscillating tool to remove plywood backing plates. Used a grinder and sanded it to make it ready for new backing plates.

Jim,

You do realize that you are talking about loss of windward performance on a 36~37' 11 ton long keel double ender by moving the chainplates 2" outboard...

[Jim Cate]

Originally Posted by Fortytwo

Jim,

You do realize that you are talking about loss of windward performance on a 36~37' 11 ton long keel double ender by moving the chainplates 2" outboard...

Good point! Not being familiar with the design, I thought there would be a considerably larger change in location... and if it is only a matter of two inches, you are right, not a big deal. And too, it isn't a design that lends itself to sparkling windward sailing in the first place!

But they still look agricultural to me, bolted to the outside of the hull!

Jim

[sardinebreath]

[QUOTE=Jim Cate;1551792]

Originally Posted by sardinebreath

G'Day S'Breath,

The loss of windward performance usually comes from having to sheet a genoa outside of the shrouds, and hence the minimum sheeting angle is greater with outboard shrouds.

Conversely, moving them outboard will not change the angular relationship of the mainsail and shrouds much at all, so no change in DW sailing. The contact spot where chafe occurs is moved a bit outboard, but this doesn't affect sailing performance.

Cheers,

Jim

Ah. Thanks! I forgot about the genoa.

[sardinebreath]

Originally Posted by Fortytwo

Removed the wood panelling. Removed the foam insulation behind the wood panelling. In the forward hanging locker I removed a shelf and in the head I cut away part of a shelf. Used a oscillating tool to cut away the glass over the chainplates. Used a grinder to cutoff the nuts on the inside that were seized (except for the one that fell off when I put a wrench on it). Hammered and punched out the bolts. Used a hydraulic jack, chain, metal bar and cribbing to pull the plates out through the toe rail. Used oscillating tool to remove plywood backing plates. Used a grinder and sanded it to make it ready for new backing plates.
.

Thanks for the explication. I might have been tempted, if I knew I was going outboard, to just cut the tops of the chaimplates off and leave the rest. After goiing to all the trouble to remove them, why not replace them in the same place?

[Fortytwo]

I didn't want to widen the hole through the toe rail to accommodate the new 3/8" thick chainplates. When the chainplates go through the toe rail, you can't see over 7 inches of them. Water egress is less likely with less holes in the boat.

[sardinebreath]

How problematic is throughbolting (whether the plates are placed outside the hull or inside) through an airex cored hull? Seems like 12 or so extra penetrations a side creates a lot of opportunities for something really bad to happen. If one were to do that, whats the best way to seal the inside of each hole before inserting the bolts? I was also wondering about maybe putting larger diameter plates on both sides of the hull to spread the load of the chainplates and the bolts (chainplates being mounted over an underlying plate). Whadya think?

[Cheechako]

Originally Posted by sardinebreath

How problematic is throughbolting (whether the plates are placed outside the hull or inside) through an airex cored hull? Seems like 12 or so extra penetrations a side creates a lot of opportunities for something really bad to happen. If one were to do that, whats the best way to seal the inside of each hole before inserting the bolts? I was also wondering about maybe putting larger diameter plates on both sides of the hull to spread the load of the chainplates and the bolts (chainplates being mounted over an underlying plate). Whadya think?

I would remove the core from the inside and build up solid glass where the chainplates are.

[roverhi]

If you are going to external chain plates, might be easier to cut the glassed in plates below the deck and use the remaining portion as backing plates.

The difference in pointing ability moving the chain plates outboard is not that big a thing. Yes, if you are recovering racer, the difference might be a big deal but for most people it's a direction you don't want to go in the first place. The few degrees in lost pointing ability won't be missed. At sea in a rough seaway, probably can't point that high in the first place.

As far as being agricultural, find food is kind of a nice thing.

[a64pilot]

Originally Posted by Cheechako

I would remove the core from the inside and build up solid glass where the chainplates are.

Even if it weren't for the water intrusion issue, how tight can you tighten the bolts before the laminate begins to crush if there is a core?

[Cheechako]

Originally Posted by a64pilot

Even if it weren't for the water intrusion issue, how tight can you tighten the bolts before the laminate begins to crush if there is a core?

That may be a concern, not sure they need to be any tighter than good and snug really though. A lot of gear is bolted on deck thru core. although best if not there too I suppose. The only alternative I can think of is to use a hole saw at each bolt from the inside, core out maybe 1.5 diameter, then epoxy in a plug of solid glass or other substantial material that is the same thickness as the core and inner glass...?

[roverhi]

Originally Posted by Cheechako

That may be a concern, not sure they need to be any tighter than good and snug really though. A lot of gear is bolted on deck thru core. although best if not there too I suppose. The only alternative I can think of is to use a hole saw at each bolt from the inside, core out maybe 1.5 diameter, then epoxy in a plug of solid glass or other substantial material that is the same thickness as the core and inner glass...?

Use a 199 bit on a dremel and rout out the core around the fastener. Fill the vacant area with thickened epoxy and redrill the hole. That will take care of the compression issues with the core. Will have to mix the epoxy really thick to stay on a vertical surface.

[sardinebreath]

Thanks for all that, guys. Never occurred to me to just replace the core in that area with solid glass. Seems like that would avoid both potential water intrusion and compressing the hull/core when tightening. Read somewhere that chainplate bolts should optimally be tightened to around 20% of breaking strength. That would be some scary compression on a cored hull.