Colvic 296 (30) chain plate position

[Artic Warrior]

My chainplates are all to the outside just by the toe rail.
Googling pictures all the other colvic 296 model seems the same.
Which means the Genoa sheets have to run on the outside of all the guard rails meaning you cannot Close Hall at all...
I want to move everything in board by about 6 or 7 inches which will be correct for the spreaders width as well..... I mean it's not a particularly brilliant Windward boat anyway I imagine but with this it means I'm not up wind as much as I would like...
Walk around area is quite wide so just having chain plate pads underneath isn't enough so I will have to make rods going down through the backs of the cupboards to the seats for strength... Which I don't mind making
Is there any other Colvic owners on here to have the same problem.

 

[Channel Sailor]

on my Jeanneau the shrouds are positioned in the middle of the side deck. The deck is the usual balsa core but could be solid core where the chain plates are. Underneath the deck is a stainless steel horizontal backing plate which is welded to a vertical ish solid stainless steel round bar (about half inch dia). This bar extends down to the main hull side stringer and in the same location is the top of a beefy transverse structural cross beam which follows the hull shape curving down over the keel area. The bottom of the steel rod has a flat plate bolted to a 90 degrees angle bracket. This angle bracket bolts to both the stringer and the curved cross beam. The deck does not take any load from the rigging.

I think this might be unusual because there is not a thick vertical plywood (grp sheathed) knee type thing bonded to the hull side and under the deck.

If the hull shape and keel are not particularly optimised for windward performance, then reducing the sheet angle might not make as much difference as you might expect.

 

[Tranona]

My chainplates are all to the outside just by the toe rail.
Googling pictures all the other colvic 296 model seems the same.
Which means the Genoa sheets have to run on the outside of all the guard rails meaning you cannot Close Hall at all...
I want to move everything in board by about 6 or 7 inches which will be correct for the spreaders width as well..... I mean it's not a particularly brilliant Windward boat anyway I imagine but with this it means I'm not up wind as much as I would like...
Walk around area is quite wide so just having chain plate pads underneath isn't enough so I will have to make rods going down through the backs of the cupboards to the seats for strength... Which I don't mind making
Is there any other Colvic owners on here to have the same problem.

No you can't move them inboard. They are there for a reason - part of the design for masthead rigs and afraid you will just have to live with it. Look at other boats of the same era with similar rigs and you will find the same type of setup. Rigs that have inboard chain plates are usually fractional rigged and designed that way to allow inboard sheeting (among other reasons), or are wider beam to allow a wide enough base without taking the shrouds out to the edge of the hull.

 

[Artic Warrior]

No you can't move them inboard. They are there for a reason - part of the design for masthead rigs and afraid you will just have to live with it. Look at other boats of the same era with similar rigs and you will find the same type of setup. Rigs that have inboard chain plates are usually fractional rigged and designed that way to allow inboard sheeting (among other reasons), or are wider beam to allow a wide enough base without taking the shrouds out to the edge of the hull.

Hi thanks for the reply.
I have Wesley Griffin as well well which is is not fractional rig and that has quite in boards rig.
And Moody 31 behind me that is also more inboard and mine.
I've seen quite a few masthead rigs where the train plates do not sit out near the toe Rail

 

[Artic Warrior]

on my Jeanneau the shrouds are positioned in the middle of the side deck. The deck is the usual balsa core but could be solid core where the chain plates are. Underneath the deck is a stainless steel horizontal backing plate which is welded to a vertical ish solid stainless steel round bar (about half inch dia). This bar extends down to the main hull side stringer and in the same location is the top of a beefy transverse structural cross beam which follows the hull shape curving down over the keel area. The bottom of the steel rod has a flat plate bolted to a 90 degrees angle bracket. This angle bracket bolts to both the stringer and the curved cross beam. The deck does not take any load from the rigging.

I think this might be unusual because there is not a thick vertical plywood (grp sheathed) knee type thing bonded to the hull side and under the deck.

If the hull shape and keel are not particularly optimised for windward performance, then reducing the sheet angle might not make as much difference as you might expect.

Ive seen many production boats similar to what you're saying... So that's why I wanted to change it

 

[Artic Warrior]

No you can't move them inboard. They are there for a reason - part of the design for masthead rigs and afraid you will just have to live with it. Look at other boats of the same era with similar rigs and you will find the same type of setup. Rigs that have inboard chain plates are usually fractional rigged and designed that way to allow inboard sheeting (among other reasons), or are wider beam to allow a wide enough base without taking the shrouds out to the edge of the hull.

I mean even for example an old westerly renown have them in the middle of the walk way... yes I know what you mean about the fractional racing yachts those are nearly against the coach roof.

 

[Tranona]

Hi thanks for the reply.
I have Wesley Griffin as well well which is is not fractional rig and that has quite in boards rig.
And Moody 31 behind me that is also more inboard and mine.
I've seen quite a few masthead rigs where the train plates do not sit out near the toe Rail

But whoever designed the rigs will have done their sums to ensure that the mast is correctly supported and that the rig loads are properly transferred the hull structure. Shortening the spreaders will narrow the angle of the shrouds and reduce the base of the lowers and therefore give less support to the mast. Chain plates on the hull provide a strong anchor point under the beamshelf/hull/deck joint. Inboard shrouds usually anchored to a bulkhead or through tie rods to take the loads down to the lower part of the hull.

 

[Artic Warrior]

But whoever designed the rigs will have done their sums to ensure that the mast is correctly supported and that the rig loads are properly transferred the hull structure. Shortening the spreaders will narrow the angle of the shrouds and reduce the base of the lowers and therefore give less support to the mast. Chain plates on the hull provide a strong anchor point under the beamshelf/hull/deck joint. Inboard shrouds usually anchored to a bulkhead or through tie rods to take the loads down to the lower part of the hull.

My spreaders are 7-foot across total and the chainplates are nearly 9 ft apart so the shrouds are at an angle which is weird.

 

[roaringgirl]

why not just lead the sheet inboard of the shrouds when close-hauled?

 

[Stemar]

I have to wonder just how much benefit you'd get from a tighter sheeting angle. I see there's a bilge keel version, and if that's what you've got, chances are the boat will always perform better if sailed a bit free. Whichever keel you have, with a boat that isn't fantastic to windward, there's a tendency to pinch, which only makes things worse. There's no benefit to pointing higher just to go slower and sideways, far better to keep the boat moving so the keel(s) have a chance. It's something I've learned the hard way!

 

[Artic Warrior]

But whoever designed the rigs will have done their sums to ensure that the mast is correctly supported and that the rig loads are properly transferred the hull structure. Shortening the spreaders will narrow the angle of the shrouds and reduce the base of the lowers and therefore give less support to the mast. Chain plates on the hull provide a strong anchor point under the beamshelf/hull/deck joint. Inboard shrouds usually anchored to a bulkhead or through tie rods to take the loads down to the lower part of the hull.

I'm not shortening the spreaders.
My spreaders measure 7 Foot cross tip to tip my chain plates are just over 9 foot apart... so the ringing is at an angle getting wider as it goes down as it is which is strange.

 

[Artic Warrior]

why not just lead the sheet inboard of the shrouds when close-hauled?

The track is right out next to the toe rail as well

 

[Artic Warrior]

I have to wonder just how much benefit you'd get from a tighter sheeting angle. I see there's a bilge keel version, and if that's what you've got, chances are the boat will always perform better if sailed a bit free. Whichever keel you have, with a boat that isn't fantastic to windward, there's a tendency to pinch, which only makes things worse. There's no benefit to pointing higher just to go slower and sideways, far better to keep the boat moving so the keel(s) have a chance. It's something I've learned the hard way!

Mine is to bilge keel version.
But they are big keels...
I'm tidal here ten meters so a fin is not an option ha ha.
But yes I hear what you're saying about baring iff and making life easier

 

[rogerthebodger]

I'm not shortening the spreaders.
My spreaders measure 7 Foot cross tip to tip my chain plates are just over 9 foot apart... so the ringing is at an angle getting wider as it goes down as it is which is strange.

No is correct that the chain plates will be wider than the spreader/s. I have 2 spreaders a side and the upper one is shorter then the next one down which is shorted then the chain plate width

 

[roaringgirl]

The track is right out next to the toe rail as well

Then moving the chain plates out wouldn't help with the sheeting angle.

 

[Rappey]

That idea seems an awful lot of work for little gain.
Could be a problem with a survey as I would think you would have no way of proving the moved chainplates are fixed as per calculated loadings etc.

 

[Channel Sailor]

on my Jeanneau the shrouds are positioned in the middle of the side deck. The deck is the usual balsa core but could be solid core where the chain plates are. Underneath the deck is a stainless steel horizontal backing plate which is welded to a vertical ish solid stainless steel round bar (about half inch dia). This bar extends down to the main hull side stringer and in the same location is the top of a beefy transverse structural cross beam which follows the hull shape curving down over the keel area. The bottom of the steel rod has a flat plate bolted to a 90 degrees angle bracket. This angle bracket bolts to both the stringer and the curved cross beam. The deck does not take any load from the rigging.

I think this might be unusual because there is not a thick vertical plywood (grp sheathed) knee type thing bonded to the hull side and under the deck.

If the hull shape and keel are not particularly optimised for windward performance, then reducing the sheet angle might not make as much difference as you might expect.

I forgot to add, It is a fractional rig.

 

[Laminar Flow]

I'm not shortening the spreaders.
My spreaders measure 7 Foot cross tip to tip my chain plates are just over 9 foot apart... so the ringing is at an angle getting wider as it goes down as it is which is strange.

Narrowing the spreader base will increase the compression load on the mast for which it may not be designed.

The formula is: MR (Max righting moment) x 1.5 (safety factor) divided by half beam mast to chain plate = compression load on mast.

Unless you know your max righting moment, which as an owner of a Colvic craft I doubt, or you have access to the lines of the boat and can calculate it for 30 degr heel, or pick a number from the S&S righting moment tables (not quite as accurate), I would leave it as is, since you might very well need a new mast to absorb the increased compression loads.

Since the spreaders on a single spreader rig are not usually in the linear centre of the mast (usually 55-60%), it makes perfect sense that the spreader span is less than the shroud base at the foot.

Unless you can get some numbers for the actual loads and can determine whether you existing mast has enough inertia to absorb the increased load I would not bother.