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,

--
Evan Gatehouse

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

If I was doing this for myself, I`d probably take a piece of stainless round
bar of a suitable diameter and machine the ends to suit the chain plate at
the bottom and the bottom of the rigging screw at the top. Dunno how this
would work on the forestay though- roller furling? Maybe best to replace the
forestay only?
Bob
Evan Gatehouse wrote:
:: 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,
::
:: --
:: Evan Gatehouse
::
:: you'll have to rewrite my email address to get to me
:: ceilydh AT 3web dot net
:: (fools the spammers)

Evan,

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.
You could use the top thimble with a shackle to make the transistion
to wire.

You might even consider replacing all the rigging with Amsteel Blue. It
works out a lot cheaper than wire and seems to be gaining a lot of
acceptance with the high performance cat sailors. It is a little
stronger than the same size wire and if the loads stay under 30% there
is very little creep once the initial stretch is removed.

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.

Evan Gatehouse wrote:
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,

--
Evan Gatehouse

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




--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

Glenn Ashmore wrote:

SNIP
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.


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?

Go back to the designer and ask the proper questions - there's lots of
aspects to this question besides rigging. What do you think you're
gonna get here - design genius - from people who put 14 tanks on their
boats? Multihulls have to be kept light.


On Sat, 04 Oct 2003 14:47:14 GMT, Jim Conlin
wrote:



Glenn Ashmore wrote:

SNIP
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.


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?

Freddy says:

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

True. And the designer will say "Replace the rigging with longer stuff".



What do you think you're
gonna get here - design genius

That hurts.....

from people who put 14 tanks on their
boats?

So will that.

Multihulls have to be kept light.

I'm not sure that "have" is the right word there. "Should" would be better,
and even then some would disagree. It all depends on why you want a cat, and
what it was designed for.

Steve
Stephen C. Baker - Yacht Designer
http://members.aol.com/SailDesign/pr...cbweb/home.htm

I believe you will find that Evan has worked for some of the biggest
name yacht designers in the business so I expect he already has that
figured out. He is just using the group as a sounding board the same
way I often do.

freddy wrote:
Go back to the designer and ask the proper questions - there's lots of
aspects to this question besides rigging. What do you think you're
gonna get here - design genius - from people who put 14 tanks on their
boats? Multihulls have to be kept light.


On Sat, 04 Oct 2003 14:47:14 GMT, Jim Conlin
wrote:



Glenn Ashmore wrote:


SNIP
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.


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?





--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

On Sat, 04 Oct 2003 15:23:48 -0400, Glenn Ashmore
wrote:

I believe you will find that Evan has worked for some of the biggest
name yacht designers in the business so I expect he already has that
figured out. He is just using the group as a sounding board the same
way I often do.

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

The responses I have seen to Freddy's suggestion seem altogether
collected. 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.

Brian (certified genius) Whatcott

On Sat, 04 Oct 2003 14:47:14 GMT, Jim Conlin
wrote something
.......and in reply I say!:

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?

If the guy intends to overcome the righting monent of a 40' cruising
catamaran while sailing, then the occasional broken stay will be a
minor excitement! G

************************************************** ****************************************
Those who can, do. Those who can't, teach.
The rest sit around and make snide comments.

Nick White --- HEAD:Hertz Music
Please remove ns from my header address to reply via email
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")
_/ )
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"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)