Cruisers Forum
 


Reply
 
Thread Tools Search this Thread Rate Thread Display Modes
Old 14-03-2021, 16:51   #1
Registered User

Join Date: Oct 2020
Location: West Palm Beach
Boat: Hunter 37C
Posts: 166
Catamaran rigging - 60 deg mast rake???

Hello y’all! So this question is simply for my own edification and I admittedly know little about catamaran rigging.
What is the benefit of the extreme rake on some catamaran masts?
I got a new neighbor and I swear his mast is at a 60degree angle. (I’m using the building window line to estimate 90 deg. So that’s where I got 60 from).
At first I thought it was damaged but it looks like it is supposed to be that way.
This seems like it would put a lot of pressure on the rigging, especially the forestay and at the base of the mast and its attachment and also greatly reduce sail area.
Obviously some naval engineer thought there was a benefit but what is it?
Thanks in advance for the info!
Attached Thumbnails
Click image for larger version

Name:	IMG_1615765492.931528.jpg
Views:	74
Size:	446.9 KB
ID:	234538  
Sailing Ohm is offline   Reply With Quote
Old 14-03-2021, 17:09   #2
Registered User
 
Spot's Avatar

Join Date: Jan 2019
Location: Minnesota, USA
Boat: 21' trailer sailor & 8' sailing dinghy
Posts: 1,040
Re: Catamaran rigging - 60 deg mast rake???

Raked indeed...
I get 76 degrees +/-
Attached Thumbnails
Click image for larger version

Name:	rake1a.jpg
Views:	43
Size:	125.8 KB
ID:	234540  
__________________
Big dreams, small boats...
Spot is offline   Reply With Quote
Old 14-03-2021, 17:16   #3
Registered User
 
Matt Johnson's Avatar

Join Date: Mar 2010
Location: Annapolis MD
Boat: Building a Max Cruise 42 cat - previous 37' aluminum mono
Posts: 2,723
Re: Catamaran rigging - 60 deg mast rake???

That's a Dean catamaran. You can google their reasoning, but it boils down to wanting more windward ability.

Matt
__________________
MJSailing - Youtube Vlog -
Matt Johnson is offline   Reply With Quote
Old 14-03-2021, 17:16   #4
Registered User

Join Date: Oct 2020
Location: West Palm Beach
Boat: Hunter 37C
Posts: 166
Re: Catamaran rigging - 60 deg mast rake???

Quote:
Originally Posted by Spot View Post
Raked indeed...
I get 76 degrees +/-


Awesome. Thanks for the exact calculation!
What did you use to find that value?

Now hopefully someone will be able to tell me why.
Sailing Ohm is offline   Reply With Quote
Old 14-03-2021, 18:19   #5
smj
Registered User

Join Date: Nov 2007
Boat: TRT 1200
Posts: 5,673
Re: Catamaran rigging - 60 deg mast rake???

I pity the rigger that has to go to the top of that mast.
smj is online now   Reply With Quote
Old 14-03-2021, 18:38   #6
Registered User
 
Spot's Avatar

Join Date: Jan 2019
Location: Minnesota, USA
Boat: 21' trailer sailor & 8' sailing dinghy
Posts: 1,040
Re: Catamaran rigging - 60 deg mast rake???

Quote:
Originally Posted by Sailing Ohm View Post
Awesome. Thanks for the exact calculation!
What did you use to find that value?

Now hopefully someone will be able to tell me why.

I took an image file and put it into QCAD which has a free entry-level version. I drew the line for the rake, then one parallel to the waterline, and used a standard angular dimension to read the angle. If the object is flat to the plane of the photographer or if the image is a scaled line drawing it works pretty well. If you know the size of the object, the image can be scaled 1:1 with the real world and rough dimensions can be taken.
__________________
Big dreams, small boats...
Spot is offline   Reply With Quote
Old 14-03-2021, 23:43   #7
Senior Cruiser
 
StuM's Avatar

Cruisers Forum Supporter

Join Date: Nov 2013
Location: Port Moresby,Papua New Guinea
Boat: FP Belize Maestro 43 and OPBs
Posts: 11,532
Re: Catamaran rigging - 60 deg mast rake???

Interestingly, everything I've seen says that Deans have a 7° rake, that one is twice that!
StuM is offline   Reply With Quote
Old 15-03-2021, 02:26   #8
Registered User
 
chrisr's Avatar

Join Date: Dec 2016
Location: Australia
Boat: Tasman 40' catamaran
Posts: 1,327
Re: Catamaran rigging - 60 deg mast rake???

i'm on the same angle as stum...i've always called mast rake as the angle between the mast and vertical ie a mast raked aft 5 deg or 10 deg etc

so personally i'd be saying this boat has a rake of 14 deg

maybe others disagree ?

as regards the reason for mast rake : the aim is to improve upwind performance by moving the CoE for the rig further aft and thereby force the boat to turn up towards the wind more. it'd used when for some reason or other it's not possible to move the mast further aft

often a feature on mainly downwind boats that need all the help they can get to go upwind

not a great fan of extreme rake myself as it's a half arsed solution...

cheers,
__________________
"home is where the anchor drops"...green light from medics and travels resumed...heading somewhere warmer.
maintaining social distancing !
chrisr is offline   Reply With Quote
Old 15-03-2021, 07:58   #9
Registered User

Join Date: Oct 2020
Location: West Palm Beach
Boat: Hunter 37C
Posts: 166
Re: Catamaran rigging - 60 deg mast rake???

Thanks for the info y’all and clarification about mast rake.
I do agree that the degree should be called the offset between the rake degree and 90deg. That makes sense.
Always trying to learn new things and luckily sail boats always have new things to teach.
Sailing Ohm is offline   Reply With Quote
Old 15-03-2021, 09:22   #10
Registered User
 
MV Caroline's Avatar

Join Date: Jan 2020
Location: aboard
Boat: Custom built Skookum 53' trawler
Posts: 43
Re: Catamaran rigging - 60 deg mast rake???

Quote:
Originally Posted by Matt Johnson View Post
That's a Dean catamaran. You can google their reasoning, but it boils down to wanting more windward ability.

Matt
And, obviously, increased weather helm.
MV Caroline is offline   Reply With Quote
Old 15-03-2021, 09:23   #11
Registered User

Join Date: Oct 2013
Location: Ladys Island, SC
Boat: Catalina-Morgan 504
Posts: 283
Re: Catamaran rigging - 60 deg mast rake???

Quote:
Originally Posted by Matt Johnson View Post
That's a Dean catamaran. You can google their reasoning, but it boils down to wanting more windward ability.

Matt

Lay the mast down on the deck and it will go to windward even better.
Wallaby is offline   Reply With Quote
Old 15-03-2021, 09:25   #12
Registered User

Join Date: Jun 2011
Posts: 78
Re: Catamaran rigging - 60 deg mast rake???

Reasons for : correcting weather helm, easier to come about - longer 'chord' or lower aspect ratio of mainsail. Reasons against : more stress on forestay (but less on mainsheet), horizontal stress on mastfoot, more longitutenal compression on mast, and, looks terrible ugly if over 10 degrees.

Capt. Claus - ocean tramp of the eighties
clakiep is offline   Reply With Quote
Old 15-03-2021, 10:10   #13
Registered User
 
mikereed100's Avatar

Join Date: Dec 2005
Location: Cat in Chile, trawler in Ventura
Boat: 46' custom cat "Rum Doxy", Roughwater 41"Abreojos"
Posts: 1,922
Images: 2
Re: Catamaran rigging - 60 deg mast rake???

There are a lot of reasons for mast rake on a cat:

1. To balance the rig when the mast is stepped far forward.
2. Cats can flex a lot and don't have backstays. A pronounced rake can make it easier to achieve forestay tension for windward ability.
3. The rake allows gravity to take some of the compression forces from the full battens off the sail track making it easier to raise and lower the main.
4. It looks cool.

Most cats measure rake from the vertical, so in the case of the Dean above, the rake would be 14.4 degrees.
__________________
Mike

www.sailblogs.com/member/rumdoxy

Come to the dark side. We have donuts.
mikereed100 is offline   Reply With Quote
Old 15-03-2021, 10:11   #14
Registered User

Join Date: Dec 2019
Posts: 2
Re: Catamaran rigging - 60 deg mast rake???

Is there a reason why the mast would be raked to 76° or so, rather than extending the boom longer and moving the coefficient towards aft that way?

Seems that would also work, but I guess there could be complications to that. It seems that raking the mass just illuminates a triangle of the luff of the main sail

Maybe they are already doing a combo approach to this Challenge, going up wind as much as possible

Cheers!

DL
Don Lobo is offline   Reply With Quote
Old 15-03-2021, 10:25   #15
Registered User

Join Date: Dec 2018
Location: Wichita/Pensacola
Boat: Lagoon TPI 37'
Posts: 416
Re: Catamaran rigging - 60 deg mast rake???

My rigger told me to hang a bucketful of water from the halyard and move it aft till the halyard (center of bucket) was 4' from the mast base. Then put a 9" bend in the mast. So I did. Seems to work.
14 degrees seems excessive.

Loved the comment, I would hate to climb that mast.
sailingchiro is offline   Reply With Quote
Reply

Tags
catamaran, mast, rigging

Thread Tools Search this Thread
Search this Thread:

Advanced Search
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


Similar Threads
Thread Thread Starter Forum Replies Last Post
Mast rake , can effect mast pumping?? gmakhs Construction, Maintenance & Refit 23 09-09-2018 16:11
ECN Nav: Deg:Min or Deg.Decimal? MarkJ Navigation 2 03-04-2013 09:17
Mast Rake PEACETIME Deck hardware: Rigging, Sails & Hoisting 1 25-02-2012 09:03
68 cm of Rake in a Ten-Meter Mast . . . Way Too Much Rake ? JuanCH Monohull Sailboats 13 01-11-2011 10:46
-24 deg F or -31 deg C!!!!! Heater news ssullivan Plumbing Systems and Fixtures 8 06-01-2008 23:41

Advertise Here


All times are GMT -7. The time now is 12:55.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2021, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2021, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.