Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 03-09-2015, 10:57   #421
Marine Service Provider
 
beiland's Avatar

Join Date: Aug 2007
Location: St Augustine, FL, Thailand
Boat: 65 Sailing/Fishing catamaran
Posts: 1,142
AftMast Ketch on a Big Trimaran

The Ketch-Rigged Cat
__________________

__________________
beiland is offline   Reply With Quote
Old 03-09-2015, 12:06   #422
Registered User
 
Skip JayR's Avatar

Join Date: Jul 2015
Location: see https://trienthusiasts.wordpress.com/
Boat: still looking for the right Tri
Posts: 430
Re: The Death of the Ketch ?

Quote:
Originally Posted by Greatketch33 View Post
I think the discussion about ketch rigged boats is lively. This is a great post to learn and share.


I absolutely agree.... makes me very happy. (Rec.: I was out of sailing for more than 10 years and find back in 2015 to this thematic hopefully being on the boat then in 2016 again). - I am not a sailor who likes to hang around over winter till spring time to repair a boat, paint it etc. ... I hate that part and hopefully never must do it as soon I have my own boat (probably it wont come that way).

Sailing for me is not just being on the water... its more all the things around, mostly its steadily learning.... e.g. visiting boat shows... sitting in the class room of a sailing school and teach, or sitting in a sailing club and learn from experienced sailors, reading books about technical aspects of sailing or biographies of round the world sailors. So it was till the 90th.

Luckily nowadays more easily we can share our passion and interests, globally. I am German native so I should not complain about as I am living in a region where exist plenty of sailing clubs etc. ...
But there are many people out there who only can learn, share and get support via Internet because they live in a landscape with "bad infrastructure".

The Internet nowadays is a great tool for plannings.... getting harbour maps, nautical datas, weather maps in real time etc. ... so I would say: Modern sailing in 21st century became more exiting. But same it needs seriously thinking about the substance of sailing (and water sports in general).

We never should forget what sailing means in its purest form. For the newbees, watch this to understand and for the "old ones" to remember from where yachting originally comes - by spirit.


When I was professional skippering in the 90th I waited full of excitement for the next edition of a yacht magazine... I went into the railway station and airport shops with "international press" to get the extremely expensive "international editions" to know about sailing in other regions of the world.

Nowadays we just can do all this with some few mouse clicks, front a desktop or even with mobile devices, staying on a boat anywhere in the world...

Its great for the younger generation they can learn so easily and quickly about sailing. Maybe its going too quick, as the time hanging around in the sailing club one should not miss, but not just for drinking a beer in the marina bar. :-)

So keep going sharing "sailing knowledge" in the sense of a chinese saying: "if two each own an egg and (s)he keeps it for her/himself, each has one egg. If each shares with the other own egg, both have two eggs."
__________________

__________________
Skip JayR is offline   Reply With Quote
Old 03-09-2015, 17:39   #423
Registered User
 
Nicholson58's Avatar

Join Date: Jan 2011
Location: Live aboard
Boat: Camper & Nicholson58 Ketch - ROXY Traverse City, Michigan No.668283
Posts: 3,466
Images: 83
Re: The Death of the Ketch ?

Quote:
Originally Posted by Training Wheels View Post
Slootch?


Sent from my iPhone using Cruisers Sailing Forum
SCOTCH?
__________________
Nicholson58 is offline   Reply With Quote
Old 03-09-2015, 22:13   #424
Registered User
 
MarinerJo's Avatar

Join Date: Aug 2011
Location: Seattle,Wa
Posts: 202
Re: The Death of the Ketch ?

Quote:
Originally Posted by Nicholson58 View Post
SCOTCH?
I'll take two, please.
__________________
Time you enjoyed wasting wasn't wasted
MarinerJo is offline   Reply With Quote
Old 03-09-2015, 22:36   #425
Senior Cruiser
 
Jim Cate's Avatar

Cruisers Forum Supporter

Join Date: May 2008
Location: cruising SW Pacific
Boat: Jon Sayer 1-off 46 ft fract rig sloop strip plank in W Red Cedar
Posts: 11,461
Re: The Death of the Ketch ?

Quote:
Originally Posted by Skip JayR View Post
wowh.... lots of new input over night :-) Maybe we can keep it with little bit more structure ???



In the sub-division "Multihulls" is going a discussion specifically about "The Ketch-Rigged Cat" :-)
Structured?? Are you serious? This is the internet...

And BTW, the gentleman that you are chiding is talking about a cat ketch, not a ketch rigged catamaran. There is a difference.

Jim
__________________
Jim and Ann s/v Insatiable II , lying Port Cygnet, Tasmania once again
Jim Cate is offline   Reply With Quote
Old 04-09-2015, 09:13   #426
Registered User

Join Date: Jun 2014
Location: San Diego, CA
Boat: Beneteau Oceanis 38
Posts: 563
Re: Vertical Backstay

Quote:
Originally Posted by beiland View Post
If that stay (backstay) were run 'parallel to the mast' it would NOT exert a back force to offset the forestay's force. In fact it preferable needs to come off the masthead at an angle close to that of the forestay.
How will the the side-loads be handled with no port/starboard stays on that aft sail? With just a fore-aft spreader bringing the halyard block aft, there's nothing to support that sail side-to-side. Unless I'm missing something? The side forces would break the fore-aft spreader pretty quickly.
__________________
mstrebe is offline   Reply With Quote
Old 04-09-2015, 12:25   #427
Marine Service Provider
 
beiland's Avatar

Join Date: Aug 2007
Location: St Augustine, FL, Thailand
Boat: 65 Sailing/Fishing catamaran
Posts: 1,142
Re: Vertical Backstay

Quote:
Originally Posted by mstrebe View Post
How will the the side-loads be handled with no port/starboard stays on that aft sail? With just a fore-aft spreader bringing the halyard block aft, there's nothing to support that sail side-to-side. Unless I'm missing something? The side forces would break the fore-aft spreader pretty quickly.
Several thoughts there.
1) In the first place the shortest distance for that major aft masthead backstay to assume, particularly in its highly loaded condition is the straight line over the aft jumper strut and down towards the mast step structure/bulkhead. If it is composed of a material that does not stretch much, it is not going to elongate that much out of that shortest straight line.
Sure the side loading of the mizzen's head will try to bend things off to the side a little bit, but what will that matter if the jumper strut is mounted to the mast in a 'flexible manner' (pinned to allow such a minor swing). Besides who will care if the mizzen sail operates slightly 'off center' . The important thing is to not let the aft jumper strut impart a rotation force on the mast tube. ....Or several other ideas in mind.
2) As I believe I posted somewhere before. there could be a couple of other alternatives,...2 minor backstays attached to the outer tip of that aft jumper strut, or some rigging links over to the athwartships spreader tips at that location.
__________________
beiland is offline   Reply With Quote
Old 04-09-2015, 13:23   #428
Registered User

Join Date: Jun 2014
Location: San Diego, CA
Boat: Beneteau Oceanis 38
Posts: 563
Re: Vertical Backstay

Quote:
Originally Posted by beiland View Post
Several thoughts there.
1) In the first place the shortest distance for that major aft masthead backstay to assume, particularly in its highly loaded condition is the straight line over the aft jumper strut and down towards the mast step structure/bulkhead. If it is composed of a material that does not stretch much, it is not going to elongate that much out of that shortest straight line.
Sure the side loading of the mizzen's head will try to bend things off to the side a little bit, but what will that matter if the jumper strut is mounted to the mast in a 'flexible manner' (pinned to allow such a minor swing). Besides who will care if the mizzen sail operates slightly 'off center' . The important thing is to not let the aft jumper strut impart a rotation force on the mast tube. ....Or several other ideas in mind.
2) As I believe I posted somewhere before. there could be a couple of other alternatives,...2 minor backstays attached to the outer tip of that aft jumper strut, or some rigging links over to the athwartships spreader tips at that location.
So with the high tension on the back stay (which the fore-aft spreader has to counter) and little to no stretch, side load forces that are allowed to move the backstay side-to-side will necessarily pull the mast backwards from the peak. Furthermore, since the mast is also back-stayed right below this fore-aft spreader, the entire flex in the mast to tolerate the side-side motion will come only from the upper mast portion from the spreader up. With the compression of the spreader against the mast and this back tension, typical aluminum will break right at the spreader bar unless it's heavily reinforced, adding weight aloft.

I think the simplest solution is to simply make the mast straight up, such that the mizzen main (I guess I'll call it) is vertical to it, and angling the two headsails a bit more along their leech to reach it. The mast would have to be taller, but that's a much easier problem to solve.

Another potential solution is two masts (like a ketch) but both stepped at the same location, one raked forward as you have it and one going straight up to support the mizzen. This aft mast could then be properly stayed.

You will need to model the rig tension to determine how problematic this really is. New synthetic rigging can almost certainly handle the tensions involved, the question in my mind is whether the mast and chainplates can.
__________________
mstrebe is offline   Reply With Quote
Old 05-09-2015, 08:49   #429
Marine Service Provider
 
beiland's Avatar

Join Date: Aug 2007
Location: St Augustine, FL, Thailand
Boat: 65 Sailing/Fishing catamaran
Posts: 1,142
Orca, 'wishbone' aftmast

Just searching for some of my postings to answer your questions MSTREBE, and I ran across this monohull with an A-frame or 'wishbone' aftmast.

Aftmast rigs??? - Page 24 - Boat Design Forums
Attached Thumbnails
Click image for larger version

Name:	Orca,PtWilson,Oct2010.jpg
Views:	78
Size:	60.5 KB
ID:	108469  
__________________
Brian Eiland
distinctive exploration yachts
beiland is offline   Reply With Quote
Old 05-09-2015, 09:13   #430
Marine Service Provider
 
beiland's Avatar

Join Date: Aug 2007
Location: St Augustine, FL, Thailand
Boat: 65 Sailing/Fishing catamaran
Posts: 1,142
Vertical Backstay

Quote:
Originally Posted by mstrebe View Post
How will the the side-loads be handled with no port/starboard stays on that aft sail? With just a fore-aft spreader bringing the halyard block aft, there's nothing to support that sail side-to-side. Unless I'm missing something? The side forces would break the fore-aft spreader pretty quickly.
Found one of those postings I had made on the 'additional backstays' to the aft jumper strut (fore-to-aft spreader as you termed it)

Aftmast rigs??? - Page 24 - Boat Design Forums
__________________
beiland is offline   Reply With Quote
Old 05-09-2015, 09:18   #431
Marine Service Provider
 
beiland's Avatar

Join Date: Aug 2007
Location: St Augustine, FL, Thailand
Boat: 65 Sailing/Fishing catamaran
Posts: 1,142
Sagging Forestays,...all detrimental?

Found some other good postings in that long subject thread where I have attempted to define my aftmast rig.

This one should interest some naysayers, Sagging Forestays
__________________
Brian Eiland
distinctive exploration yachts
beiland is offline   Reply With Quote
Old 07-09-2015, 08:17   #432
Marine Service Provider
 
beiland's Avatar

Join Date: Aug 2007
Location: St Augustine, FL, Thailand
Boat: 65 Sailing/Fishing catamaran
Posts: 1,142
Re: AftMast Ketch on a Big Trimaran

Just wondered if anyone bothered to look at this link?...

Quote:
Originally Posted by beiland View Post
Quote:
Originally Posted by brian eiland View Post
Aft Mast Alternative on Big Trimaran

Several years ago I was asked by a gentleman to come have a look at a big Kurt Hughes trimaran he was building, a 63 footer he had stretched to 65, if I remember correctly. He was VERY concerned about handling that big mainsail on that big sloop rig.

I spent a week as his guess at his home, and in the huge building shed outback he had erected to build this ultimate retirement vessel for himself, his wife and his kids. He is of Romanian decent, and has that Italian flare for home wine making (and drinking). Needless to say we had LOTS of fun drinking all sorts of home brewed wines and talking boats.

Here is what I came up with as a solution for him in the context of my mast aft theme. Please realize I was restricted by the existing structure of the vessel that was already well under way in construction...i.e., bulkhead placements, crossbeams, etc, etc.

There was one other nagging question he had, that needed to be taken into account....what if the fwd leaning mast idea would not work?? This persisted to be such a big question in his mind that I had to give considerations as to how my mast aft design could be converted back to a more standard rig configuration without a great deal of expense, and/or trouble to him.

I still chose an 'all-3 sails-furling' arrangement....my single-masted ketch concept. But I made the mast rake almost half (6 degrees) of the original design. And the mizzen sail was made a bit larger in proportion. Thus this rig could be converted to a straight standing cutter rig with the mizzen becoming a more traditional mainsail attached to the aft edge of the mast. Or a new larger mainsail could be constructed for the mast that could be extended upward (taller), but still stepped in same location. The cutter jibs would then both be fractional, but would not require modification.

Over all I sought to give him the same total sail area as the original design by Kurt Hughes. This was approx 1900 sq ft. BUT notice what happened to the mast height on these two versions !! The original sloop rig carried a 92' high rig. My rig carries that same sail area on a 73.5 foot mast !

With this significant reduction in the rig height and the 'all-furling' feature, I imagine this gentleman will be able to handle this rig without a lot of additional assistance, and he may well be able to SAFELY sail into higher wind conditions without as much fear of being overpowered....his sailing efficiency should be improved.

I had two options for the lower backstays here...1) anchored to the aft crossbeam ends (at a 13 degree angle to the mast), or 2) anchored to the ama hull ends (at a 20 degree angle). Both of these backstay angles are better than my original design, thus even less loading reqired of these backstays to offset the inner forestay loads.

I felt this shorter rig could justify a slightly shorter daggerboard, and we opted to move that daggerboard slightly forward to both be in a better balance with the new sail plan, and to better fit in with a saloon modification he had already planned.

To my knowledge at this time he is still thinking about his final rig design options, and his boat building processes have been put into a holding pattern while he attends to converting that original building shop into a multiple house dwelling. He then intends to build an even bigger shed to complete final assembly of this very big beamy trimaran. I'm not sure if he will chose my mast aft option, but I would be willing to place bets on it being a very good one for his needs.

[NOTE: The second aftmast sketch represents a more current modification of the masthead attachment of its backstay, and the ama anchoring of the lower backstay(s). These are just suggested options to the original sketch, and certainly not final ideas]
Attached Thumbnails
Click image for larger version

Name:	Kurt Hughes 63 Tri.JPG
Views:	94
Size:	120.9 KB
ID:	108565   Click image for larger version

Name:	AftMast 63 Tri, graphic fix.jpg
Views:	107
Size:	64.1 KB
ID:	108566  

Click image for larger version

Name:	AftMast 63 mod, graphic fix.jpg
Views:	105
Size:	124.9 KB
ID:	108567  
__________________
Brian Eiland
distinctive exploration yachts
beiland is offline   Reply With Quote
Old 07-09-2015, 11:29   #433
Registered User
 
neilpride's Avatar

Join Date: Jul 2009
Location: in the world
Boat: csy 44 tall rig.
Posts: 3,099
Re: The Death of the Ketch ?

I take my time to read that web site, still dont understand the concept... or the real benefit .
__________________
neilpride is offline   Reply With Quote
Old 07-09-2015, 11:51   #434
Marine Service Provider
 
beiland's Avatar

Join Date: Aug 2007
Location: St Augustine, FL, Thailand
Boat: 65 Sailing/Fishing catamaran
Posts: 1,142
Re: The Death of the Ketch ?

Quote:
Originally Posted by neilpride View Post
I take my time to read that web site, still dont understand the concept... or the real benefit .
Are you taking about reading;
1) a 'website',
2) or a particular forum posting,
3) or a rig concept as a whole
....that you don't understand??
__________________
beiland is offline   Reply With Quote
Old 07-09-2015, 12:29   #435
Registered User
 
VinnyVincent's Avatar

Join Date: Nov 2014
Location: Kemah TX
Boat: Newport 28
Posts: 331
Re: The Death of the Ketch ?

Quote:
Originally Posted by Skip JayR View Post


I absolutely agree.... makes me very happy. (Rec.: I was out of sailing for more than 10 years and find back in 2015 to this thematic hopefully being on the boat then in 2016 again). - I am not a sailor who likes to hang around over winter till spring time to repair a boat, paint it etc. ... I hate that part and hopefully never must do it as soon I have my own boat (probably it wont come that way).

Sailing for me is not just being on the water... its more all the things around, mostly its steadily learning.... e.g. visiting boat shows... sitting in the class room of a sailing school and teach, or sitting in a sailing club and learn from experienced sailors, reading books about technical aspects of sailing or biographies of round the world sailors. So it was till the 90th.

Luckily nowadays more easily we can share our passion and interests, globally. I am German native so I should not complain about as I am living in a region where exist plenty of sailing clubs etc. ...
But there are many people out there who only can learn, share and get support via Internet because they live in a landscape with "bad infrastructure".

The Internet nowadays is a great tool for plannings.... getting harbour maps, nautical datas, weather maps in real time etc. ... so I would say: Modern sailing in 21st century became more exiting. But same it needs seriously thinking about the substance of sailing (and water sports in general).

We never should forget what sailing means in its purest form. For the newbees, watch this to understand and for the "old ones" to remember from where yachting originally comes - by spirit.


When I was professional skippering in the 90th I waited full of excitement for the next edition of a yacht magazine... I went into the railway station and airport shops with "international press" to get the extremely expensive "international editions" to know about sailing in other regions of the world.

Nowadays we just can do all this with some few mouse clicks, front a desktop or even with mobile devices, staying on a boat anywhere in the world...

Its great for the younger generation they can learn so easily and quickly about sailing. Maybe its going too quick, as the time hanging around in the sailing club one should not miss, but not just for drinking a beer in the marina bar. :-)

So keep going sharing "sailing knowledge" in the sense of a chinese saying: "if two each own an egg and (s)he keeps it for her/himself, each has one egg. If each shares with the other own egg, both have two eggs."
Coolvideo Know of any more like it?
__________________

__________________
VinnyVincent is offline   Reply With Quote
Reply

Tags
ketch, paracelle

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off




Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 09:59.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.