You've gotten most, but not all of the following in the previous
comments:

1) Raising the sails increases the moment arm, which increases shroud
loads.

2) Adding weight increases the righting moment which increases shroud
loads.

3) Adding weight is to be avoided in a cat. This sounds like a major
increase.

4) Increasing the mast height reduces the shroud angle for the lowers,
thereby increasing loading on the lowers.

5) Reducing the shroud angle will require bending or replacing the
lower chainplates to match the new angle. Don't ignore this. (The
headstay and backstay have the same problem, but it's over at least
double the distance, so a toggle may be enough).

All of which suggest some careful analysis and, perhaps, bigger
shrouds.

Assuming you've done that analysis, and have determined that the
present wire sizes are still satisfactory, then I would:

1) Consider the age of the existing rigging, (I'm guessing this is a
used boat), and its remaining useful life. A complete replacement may
be in order soon anyway.

2) Consider cutting the long pieces of the existing rigging for use in
the shorter places, replacing only the longest pieces of wire, and
putting new terminations on the cut ends.

3) Look around for a used longer mast and buying its rigging or the
whole thing.

4) If you decide to piece out the rig with new two foot lengths, use
Norseman or StaLok rather than swaged fittings. A lot more money than
swaged, but a lot better quality. Then, some day down the road, you
can buy new wire and replace the two foot pieces with full length
pieces, reusing the fittings.

5) Easiest, and cheapest, would be to make extenders out of solid
stainless. Bob suggested round stock. He may have had the following
in mind, but I'll flesh it out a little. Get a second turnbuckle of
the same size as each existing one and approximately 24" long threaded
rod to match. Drill the ends of the rod for cotter pins. Take the
right hand thread end out of the existing and new turnbuckles and
thread them on the rod. Presto, you have a super-turnbuckle that will
span the gap. Get rolled threads on the rod -- if you buy the rod,
this will be almost automatic, but don't cut the threads with a die or
on a lathe. Use 316 -- it's not quite as strong as 303/304, but
corrosion is an issue here.

6) If you decide on the second solution, "just reweld the gooseneck 2'
higher", consult with the mast manufacturer. Many masts are made from
heat treated alloys that shouldn't be welded after heat treat and
there may be reinforcement inside the mast at the existing gooseneck.

Jim Woodward
www.mvFintry.com

"Evan Gatehouse" wrote in message ...
Folks,

First a bit of background. I'm considering buying a 40' cruising catamaran.
It's an "open bridgedeck" design - without a bridgedeck cabin. I want a
bridgedeck cabin so I'd have to build the cabin.

To make the cabin fit I'd have to raise the boom. I have 2 solutions - just
reweld the gooseneck on 2' higher, and trim the bottom of the mainsail.
This looses me sail area which I am loath to do.

The other solution is to raise the mast 2' (which is easy to do 'cause it's
just stepped on a deck beam). But then all the rigging wires become too
short. So I'm looking for ideas to extend rigging wires. So far I have:

- replace most of the wires (7 at least would have to be done, not a cheap
proposition)
- short lengths of rigging wire with swaged fittings at each end -
reasonably cheap but lots more potential failure points
- short lengths of multiple passes of spectra or similar high modulus line -
probably cheapest and lightest, need some custom solid aluminum thimbles to
handle the lines

I'd appreciate any opinions. Thanks,

Brian says:

Perhaps better to remember that this anonymous poster
also recommended arson as the winterizing recipe for a personal
water vehicle, in order to help you summon the replies he deserves.

Can you think of a better recipe? ;-P

Brian (certified genius) Whatcott

Is that "I'm certified AS a genius", or "I'm a genius and Certified?..."

Steve

"Glenn Ashmore" wrote

Synthetic rigging seems to be big with multihulls these days. Precourt
in Canada http://www.precourt.ca/ makes deadeyes up to 30,000 lb. just
for that purpose machined as chainplates, middle eyes and top thimbles.

yeah, that's the lanyard/deadeye's I would use. The stretch on short
lengths would be o.k.

You might even consider replacing all the rigging with Amsteel Blue. It

Yeah, but Eric Precourt doesn't recommend using it with fixed rigs (which
this boat has). Too much stretch compared to wire; it's o.k. with 3 stay
cat rigs where the mast rotates and you want a little slack.

What I want to know is how do you intend to raise the mast off that deck
beam and what will it do to the RM? You are increasing the lever arm of
the center of force and putting it up higher into stronger wind. That
in combination with reducing the angle of the stays will increase the
load on the stays. But maybe the wide base of a cat will minimize that.

Well I'm only raising it 2' - I'd certainly do the calcs but as a percentage
it isn't much. Extending it would be as simple as a little 2' aluminum pipe
compression post with welded flanges on either end.

Jim Conlin wrote:
The added accommodation will substantially increase the weight of the
boat,
increasing the righting moment. Is the existing standing rigging up to
the
increased loads?

Yes, it would increase the RM - but the overall boat + payload weight is
still within the designer's maximum number.

freddy said:

Go back to the designer and ask the proper questions - there's lots of
aspects to this question besides rigging.

True - but I'm pretty capable of handling those , it was just this
particular aspect that was something I didn't have experience with.

Ford Walton wrote:

Lanyards and deadeyes" or solid metal extensions should work, but you
could also cut 2 feet off of the top of the sail and add a short gaff or
a really substantial headboard.

I did think of just chopping 2' off the head of the sail after raising the
boom (but I want to preserve sail area).

Jim Woodward had a lot of good points especially the super turbuckle but
I'll address this one:

6) If you decide on the second solution, "just reweld the gooseneck 2'
higher", consult with the mast manufacturer. Many masts are made from
heat treated alloys that shouldn't be welded after heat treat and
there may be reinforcement inside the mast at the existing gooseneck.

Almost all masts are 6061-T6 which is a heat treated alloy that loses
strength after welding - but the existing gooseneck flanges are welded on
and seem o.k. - so another weak area 2' higher probably isn't going to
cause too much trouble. I will look into a drilled/tapped/bolted fitting.
Has anybody ever seen a reinforcement inside the mast at a gooseneck? I've
looked up a lot of mast tubes and seen a lot of mast drawings and never seen
one on an aluminum mast.

Once again thanks for all the constructive thoughts. They are apprecicated.


--
Evan Gatehouse

you'll have to rewrite my email address to get to me
ceilydh AT 3web dot net
(fools the spammers)

I will look into a drilled/tapped/bolted fitting.
If you go this route you may want to also epoxy your gooseneck in place.
It helps with corrosion and provides strength.


Has anybody ever seen a reinforcement inside the mast at a gooseneck?
No, I have only seen boom vang locations and shroud locations reinforced
but I'm sure haven't seen it all.


"Evan Gatehouse" wrote in message
...

"Glenn Ashmore" wrote

Synthetic rigging seems to be big with multihulls these days. Precourt
in Canada http://www.precourt.ca/ makes deadeyes up to 30,000 lb. just
for that purpose machined as chainplates, middle eyes and top thimbles.

yeah, that's the lanyard/deadeye's I would use. The stretch on short
lengths would be o.k.

You might even consider replacing all the rigging with Amsteel Blue. It

Yeah, but Eric Precourt doesn't recommend using it with fixed rigs (which
this boat has). Too much stretch compared to wire; it's o.k. with 3 stay
cat rigs where the mast rotates and you want a little slack.

What I want to know is how do you intend to raise the mast off that deck
beam and what will it do to the RM? You are increasing the lever arm of
the center of force and putting it up higher into stronger wind. That
in combination with reducing the angle of the stays will increase the
load on the stays. But maybe the wide base of a cat will minimize that.

Well I'm only raising it 2' - I'd certainly do the calcs but as a
percentage
it isn't much. Extending it would be as simple as a little 2' aluminum
pipe
compression post with welded flanges on either end.

Jim Conlin wrote:
The added accommodation will substantially increase the weight of the
boat,
increasing the righting moment. Is the existing standing rigging up to
the
increased loads?

Yes, it would increase the RM - but the overall boat + payload weight is
still within the designer's maximum number.

freddy said:

Go back to the designer and ask the proper questions - there's lots of
aspects to this question besides rigging.

True - but I'm pretty capable of handling those , it was just this
particular aspect that was something I didn't have experience with.

Ford Walton wrote:

Lanyards and deadeyes" or solid metal extensions should work, but you
could also cut 2 feet off of the top of the sail and add a short gaff or
a really substantial headboard.

I did think of just chopping 2' off the head of the sail after raising the
boom (but I want to preserve sail area).

Jim Woodward had a lot of good points especially the super turbuckle but
I'll address this one:

6) If you decide on the second solution, "just reweld the gooseneck 2'
higher", consult with the mast manufacturer. Many masts are made from
heat treated alloys that shouldn't be welded after heat treat and
there may be reinforcement inside the mast at the existing gooseneck.

Almost all masts are 6061-T6 which is a heat treated alloy that loses
strength after welding - but the existing gooseneck flanges are welded on
and seem o.k. - so another weak area 2' higher probably isn't going to
cause too much trouble. I will look into a drilled/tapped/bolted fitting.
Has anybody ever seen a reinforcement inside the mast at a gooseneck?
I've
looked up a lot of mast tubes and seen a lot of mast drawings and never
seen
one on an aluminum mast.

Once again thanks for all the constructive thoughts. They are
apprecicated.


--
Evan Gatehouse

you'll have to rewrite my email address to get to me
ceilydh AT 3web dot net
(fools the spammers)