new shroud plates ? help please

[sarabande]

I have found a new (2nd hand) ali mast to replace the heavy wooden one on my 24ft restoration project.

The original spar was a 3/4 rig, and had just 2 shrouds, swept back aft of the mast.

The new one is full masthead rig, has a cap shroud and 2 fore and aft lowers. It also has a beefier tabernacle.


Can I attach the cap shrouds (normally secured in line with the mast, I know) to the shroud plate about 4 inches aft of the mast centreline, or will this induce all kinds of unhelpful bends and panting ?

I'm happy to add a new plate for'd for the for'd lower, but it would be handy to avoid adding a new cap shroud plate in line with the mast.

(The boat is wood so relatively easy to add strengthening doublers down below.)

View attachment 31166


TIA

 

[saltylegs]

Your caps will probably have to be in line as that is the way your spreaders are set, and if you set your caps aft then that is likely to induce a huge amount of predend.

PS here's another one for you http://www.gumtree.com/p/for-sale/24-yacht-boat-wooden-with-inboard-diesel/1015253183 I think she was also built by Lesley Hanna

 

[William_H]

I don't think on a mast head rig the cap shroud chain plates being 4 inches aft of abeam the mast will matter. You may need to bend the spreaders slightly to avoid the cap shroud pulling the spreader tip aft (so the middle of the mast).
However you will need more chain plates aft and also forward of abeam the mast for the intermediate stays.

It might be well worth your while thinking about raising and lower the mast on a hinged tabernacle or mast base. This can mean never climbing the mast plus the ability to traverse under bridges etc.
If you have a mast head rig you can very effectively support the mast sideways through the traverse to near horizontal by maintaining cap shrouds tight. This is done by having the cap shrouds pivot aft(as the mast goes down) at a point exactly in line with the mast pivot. This is done by having a solid chain plate extending up to the required height or by extending the chain plate with a solid link (piece of tube or plate which is stayed forward by a wire). So if you did use a solid extension this could be angled forward so that cap shroud is abeam the mast from a chain plate slightly aft of abeam the mast.
PM me if you are interested and confused. olewill

 

[Seajet]

I agree with everything olewill says !

No problem having the caps slightly swept, I'm just a little concerned you're making a big change to the boat just because of the mast you've come across rather than as a deliberate plan.

The sails will be different of course, but more to the point the original rig sounds very like mine, where the swept cap shrouds do a lot of the mast restraint when running off the wind; with the new rig you should have a look at your backstay arrangement and make sure it is adequate.

Why put up with all the changes this new mast is inflicting on you ? It's very easy to add and change fittings, tangs etc, on an alloy mast.

 

[vyv_cox]

I'm looking at a masthead rigged boat right now with the rig just as the OP has questioned. Spreaders are slightly swept back, chain plates look about 6 inches aft, but it's a biggish boat. Fore and aft lowers.

 

[vyv_cox]

I walked over for a look. It's an Oceanis 351, the aft lowers and capshrouds go to more or less the same chainplate as far as I can see from the ground.

 

[Lakesailor]

I've had both and would not be happy with swept back spreaders when they should really be just involved in holding the mast perpendicular. The lowers should be dealing with pre-bend and avoiding an "S" shape in the mast. Forestay and backstay should be taking all the major loads.

I rather preferred masthead.

Just my opinion of course.

 

[vyv_cox]

The Oceanis has a masthead rig.