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-   -   28II Mainsheet system (http://www.sailnet.com/forums/newport/72889-28ii-mainsheet-system.html)

stpabr 03-18-2011 11:48 AM

28II Mainsheet system
 
Getting ready to replace all mainsheet blocks on the Newport 28II. Removed the old 5 block system and probably will maintain the 5:1. Is the winch really neccessary to haul in the mainsheet with the 5:1 system?
I'm looking at Harken Carbo 57mm blocks, which fall under the Mainsheet load calculator of 850 + or - lbs with 18 knots of wind, but the Harken Tech Rep recommends 75mm do to the chance of overloading the blocks with the winch. Hoping to keep costs down!
Also I want to use the Small Boat (22mm) traveler system with 4:1. I plan on extending the High Beam track past the U channel to put the Traveler ends on with the cams.
Also is 18 knots of wind about right for the first reef?
I have never sailed this boat and towards the end of a restoration.

Thanks,

zz4gta 03-18-2011 04:33 PM

According to this site, Mainsheet Load Calculator 20 kts apparent translates into 1069 lbs. Divide that by 5 and you get 214 on the tail. Can you pull over 200 lbs? I know I can't, that's why you have a winch. Consider adding a fine tune adjustment and doubling your purchase.

Also, you can try the smaller blocks, but if they grenade and take someone's head off, you can't sue harken. Also, the shock load on a jibe will be WAY higher than your static sailing around.

stpabr 03-18-2011 10:00 PM

I do believe when 20 knots comes, I'll be reefing down, which will change the dynamics of the Luff and foot measurements. Using 18 knots, 32.5 luff and 10.3 foot I get 790. Don't forget "D" what did you input for D?

Do you sail a Newport 28?
Come on 28 owners, what size\system is your mainsheet and traveler?

Thanks for the input!

zz4gta 03-21-2011 09:55 AM

I do not sail the Newport 28.
I put 5' for "D". The formula is very sensitive to the "D" value.
Given you're SA/D ratio, I'd probably reef at a sustained 20 kts or more depending on what headsail I was flying.

stpabr 03-25-2011 09:39 PM

Any Newport 28 sailors out there?

KeelHaulin 03-26-2011 12:08 AM

I think the wind load estimate is low. It's not unreasonable to sail without reefing the main in 20 kts true which would be higher in apparent wind. In addition there is loading in a gust or a round down. Running the calculator with your main dimensions, nominal length from the end of the boom of 3' and a max wind load of 30 kts (not unreasonable to get a +10 kt gust), the total load on the boom is 1750 lbs. That means the load on the traveler block is 1750 and the load on each of thee blocks on the boom will be 600 lbs. The 57mm single block is rated 792 lbs SWL, which should be OK (use at your own risk), but the double with becket for the traveler is too small, rated at 1584 lbs. I would use a fiddle block on the traveler, so look for one rated higher than 2000 lbs.


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