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Mast Rake

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nics0car
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Mast Rake

How much mast rake should apply to standard rig? 

newguy
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Hey Nick.  According to the owner's manual, no rake when static tuning, although many owners induce up to 6" aft when measured at the boom (done via headstay/backstay tension) and also introduce a bit of prebend (done via lowers).

Please consider adding a "signature" to your postings so we can know something about you and your boat.

Nick Caballero
Retired C36/375IA Mk II Technical Editor

Clifford Bassett
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Prior to my Catalina 36, I owned a Racing Boat with Hydraulic Backstay, but even then it required a Babystay lead forward to accomplish any significant " Bend."  I have tried to rake my Catalina Std. Rig aft, but with little results.  Newguy mentioned trying tightening the forward lowers, then applying Backstay tension and see what you get.  I did exactly this procedure this year and it did seem to work somwhat..  The Standard Rig Mast is a " Tree Trunk, " and I don't think they intended any Rake.  

Clifford Bassett
s/v " Red Dog "
1984 C-36 Hull # 260
M25 SR/FK
​Holland, Michigan
 

EUREKA
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Some years ago we added a textile  back (dyneema) and a hydraulic navtec back tensioner. Although we can not get to much rake,  it allows Eureka to point higher and flatten the main.

Regards from the Mediterranean!

Eladio Vallina

C-36 TR EUREKA II
Hull 1122 (1991)
Home port Barcelona (Spain).

KMHays735
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I just bought a Catalina 36 Mk1; a boat without a tapered mast and double spreaders is a new experience for me-the first time I sailed it I noticed it had neutral helm. I can't sail that way and Catalina direct folks tell me you can rake the mast 6" to 12". 
Do any of you have a tuning guide (other than the owner's manual); something with fore-stay length, tension measured on a Loos gauge, stuff like that?
I've diagramed the boat/rig in AutoCad and I get a fore-stay length increase from plumb to 12" of rake about 4.44"; does that sound right to anybody?
Finally, it seems to me to get any rake that you'll have to induce some bend otherwise there isn't enough room at the partners for 12" of rake.
Any help is always appreciated.

newguy
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Hey Ken.  Please consider adding a signature line to your posting.  Your name, boat name, year, sailing area, etc.

Unless a boat has an adjustable mast step or convex heel, rake in most boats is technically bend (camber).  If you look at an old schooner for example, you'll see true rake.  That being said, you CAN move the tip of the mast in relationship to the base and this will effect helm, simulating rake, but also changes the luff tension on the main (unlike true rake).  Adjusting the lowers can modify where the max camber occurs along the mast, thus also changing the luff tension on the main.
 
My normal tuning procedure is to have the mast sit “naturally” on the step with slight rig tension.  Then, drop a plumb bob from the mast top to the boom and measure rake and then from side-to-side to the cap shrouds.  Next, center the mast tip between the cap shrouds using the turnbuckles to moderate tension.  Then, wedge the partners and then take up tension on the forestay until the mast tip is pulled forward a tiny bit (using the plumb) and note the thread count in the turnbuckle.  Then, moderate tension on the backstay, making sure that the tip moves back to where it started.  At this point, you should have moderate tension on all long wires, so decide on how much you want the plumb to move aft and adjust forestay and backstay tension to achieve this, then tighten both down to something close to normal tension when done.  Then moderate and even tension on the lowers, with the forward lowers perhaps a turn tighter than the aft lowers.  Go sailing and adjust caps and lowers to control side-to-side mast bend.
 
The 4.44” of added length to the forestay seems about twice as much as I’d be comfortable with.  You have to keep in mind that loosening the turnbuckle too much will result in not enough threads engaged.  You should always be able to see a few threads in the open part of the turnbuckle.  Finally, I would not jump to the conclusion that mast bend is responsible for neutral helm (unless the mast has reverse camber, which is dangerous).  Given no reverse camber and perhaps just a straight mast, neutral or lee helm under moderate conditions would be unusual for a Catalina 36

Nick Caballero
Retired C36/375IA Mk II Technical Editor

pierview
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When you say "standard " rig do you mean standard vs tall rig or a regular sail rig vs in mast furling? If in mast furling  you wont want any rake or you'll have trouble furling the main.

Chuck Parker
HelenRita 2072 Mk II
2002 Tall Rig - Winged Keel
Atlantic Highlands, NJ

KMHays735
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Thanks for all of the input. I am pretty sure I know what I want to do and how to do it but what I was hoping for is a performance tuning guide, something a racer might use to optimize the rig setup and tension. 

I will say while delivering the boat home the down wind performance in light air was better than I expected for a heavy boat heavily loaded up with cruising gear; winged out and nearly dead down the boat's VMG was 5.5 knots in 6.7 knots of breeze (with a modest tide push).

Ken Hays
Hull # 858
Home Port: Sequim WA

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newguy
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Hey Ken.  You might try posting your question to the RACING or SAILING forum areas.  Good luck!

Nick Caballero
Retired C36/375IA Mk II Technical Editor

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