Spreader Angle and sail trim

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May 12, 2008
24
Santana 525 Bristol, PA Delaware River
I am in my second season with my 1979 Santana 525. Pretty much a racing boat. 25' and 2400 lb keelboat. We now have 3 at our club. I've noticed some differences in my pointing ability vs the others. I finally figured out my mast is different. They are running with the original mast, a Kenyon 3049 tear drop shaped mast and I'm running with an oval shaped mast of similar size in circumference. But the bigger difference is I noticed last week that the spreader angle on my rig is maybe 10% vs the sock rig which is maybe 30 or 35%. Single spreader rig. My spreader bars are pretty close to the same length if not identical

How do you think this affects the pointing ability of the boat? It probably affects mast bend and could be why my main looks so crappy most of the time. Should I fix it and change the spreader angle?

Thanks,

John.
 
Nov 8, 2010
11,386
Beneteau First 36.7 & 260 Minneapolis MN & Bayfield WI
Are your V1 shrouds perfectly vertical? They should go straight up from the deck chain plates to the spreader tips. If the chain plates were designed with that mast/spreaders in mind, they will be. If the mast was changed and they are angled forward to meet the less swept spreaders, you have a problem. On a highly fractional boat like the 525, the spreader angle helps support the mast loads aft.
 
Apr 8, 2010
1,606
Frers 33 41426 Westport, CT
Simple answer, if your main is cut for the other mast with the different prebend, you probably need to get a new main, unless you can match the prebend with this mast.
 

RichH

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Feb 14, 2005
4,773
Tayana 37 cutter; I20/M20 SCOWS Worton Creek, MD
Before I can answer, you'll have to define WHICH spreader angle you are describing: the vertical angle that the spreader makes with the mast, or the fore/aft angle in the horizontal plane ('swept back' spreaders).

Also you should define if those Kenyon masts are 'tapered' (increasingly smaller and smaller cross section from the mid section all the way to near the 'top' with an extension 'moment arm bar' facing aft at the top (looks like a large 'spinnaker crane' which is facing backwards and with the backstay attached to the very aft end of this 'arm' instead of being connected to the mast proper ... pretty common with Kenyon masts of this type (mid 1980s) for 'hot' boats --- if tapered you should see where the mast had a thin/long 'wedge' cut from the sides of the upper mast section, the remaining section brought together and then 'welded'. And if yours is of similar configuration or a simple 'straight pole'. Tapered mast vs. 'telephone pole' mast. ;-)
 
May 12, 2008
24
Santana 525 Bristol, PA Delaware River
Both my mast and the stock mast have non tapered cross sections. Same diameter from top to bottom. I'm talking about the spreader angle fore and aft.
 

RichH

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Feb 14, 2005
4,773
Tayana 37 cutter; I20/M20 SCOWS Worton Creek, MD
OK, In that case the only 'requirement' is that the tip of the spreader be exactly 'inline' in-plane, acually) between the top of the mast connection and the connection/fitting at the top of the chainplate.

Pointing ability is due to many factors - correct rig tension so that the jib has the proper luff curve; proper position (fore/aft) positiion (proper amount of halyard/cunningham strain so that the boat has very slight weather helm); the the second from the top aft end of the batten is somewhat parallel to the boats centerline, that the distance between the mainsail and the leech of the jib is correct (adjusting either jibsheet tension or barberhauler or 'both') to get max. speed as read on the speedo; AND most important - that ALL the telltales at the luff/midcord - and especially the tales at the leeches - are streaming straight back .... AND that the helmsman continually slightly heads up and bears off to continually 'test' the tell tale.

This insures that the boatspeed for given windspeed and wave conditions is the 'fastest', the boat is heading in the 'right' direction, the sail SHAPE is optimized for 'speed' and not 'power', the helmsman and crew are actively watching the compass to take the best advantage of a lift or to tack over on a header, which side of the course is 'paying off' in windspeed and wind direction ... once you dial-up with your sail trim and shape settings, you just cant sit there and drive the boat in a straight line tack.

Also too, the underwater 'smoothness' is vitally important, especially the smoothness at the bow, and leading edge of the keel and rudder. The hull will never be fast if youre dragging along several 'buckets full' of hull roughness.
 
May 12, 2008
24
Santana 525 Bristol, PA Delaware River
Thanks for the response. I'd say my bottom and keel are in extremely good shape for a club racer, smooth and clean. I'm thinking because my spreaders are more forward than my competition I'm unable to sheet in the genoa as much as they can without pinching the sail up against the spreader tip. I definitely need to see if I can get the tip over the chainplate and in the correct position. Rig tension and mast bend were going to be the thing I tackle this year and adjust. Looks like figuring out how to get the spreaders swept back more will be up on the list.
 
Nov 28, 2009
495
Catalina 30 St. Croix
Remove the mast and also the spreader bars that go through the mast. You can heat bend them or cold bend depending on the material to the proper angle. Trim the inboard enf of the spreaders to match the new angle of 30%. Now you have the spreader tips over the chain plates. If you like the straighter angle then move the chain plates forward. That will give you deeper down wind angles.
 
May 12, 2008
24
Santana 525 Bristol, PA Delaware River
Cayennita said:
Remove the mast and also the spreader bars that go through the mast. You can heat bend them or cold bend depending on the material to the proper angle. Trim the inboard enf of the spreaders to match the new angle of 30%. Now you have the spreader tips over the chain plates. If you like the straighter angle then move the chain plates forward. That will give you deeper down wind angles.
I like that ideas first I'm going to contact rigrite and see if they have hardware that will work without bending. Thinking if cutting the inboard ends to the correct angle but it couldn't be that easy. Right?
 

RichH

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Feb 14, 2005
4,773
Tayana 37 cutter; I20/M20 SCOWS Worton Creek, MD
John - exactly how far in from the rail is the chainplate located on this boat? I have located the plan and profile sketches for your boat .... but not enough detail of exactly 'how far in from the rail' the chainplate is located. I'll save any further comments until you advise. Approx. distances are ok. On the other boats, where is the genoa track and where is the chainplate .... how far 'in' from the rail?
This boat is VERY beamy for its length and that may be one of the items that may need a 'workaround', especially if the chainplate and the jib track and fairlead car is AT the rail.

Lemme know.

I live about 45 minutes from Bristol ..... perhaps I can stop by and do a 'look see' on my way to the Chesapeake. , etc. if the dimension info from you doesnt 'compute'.

;-)
 
Jun 9, 2008
1,771
- -- -Bayfield
YOu have gotten a lot of good information above and I don't have to add much more, but I do have a little story to tell......If your mast is not original and not exactly designed the same then you can have problems. Once I sold Seaward boats (now Hake Yachts out of Stuart FL) and they had a main bulkhead that was staggered in that the port side was more forward than the starboard one (I think a 4 or 5 inch difference on the plane). One of our customers was complaining that his main didn't look right. I went out to see what was going on and realized that the port chain plate was 4 or 5 inches forward or aft (I don't recall which bulkhead was forward or aft now) than the other. If you measured from the stemhead fitting there was a big difference in the location of the two chain plates where the uppers and lowers attached. The spreaders were designed to be straight out, not angled - or at right angles to the keel line. Well, you can imagine what this did to the mast shape. Besides twisting the mast, it brought the center of the mast aft which is inconsisent with the bias of the mainsail. I called up Hake and asked him if they built all of this model the same way and they said they did and so I told him all of those model boats were not right. The response was, "well, there are a lot of horror stories out there in the marine industry" and I thought, ya, and they are created by people like you. Well, to Hake's favor, they made the same modificationI made to my customer's boat and then later ditched that model and retooled another that was much better. But, I have to add a spacer block to the bulkhead on the forward side, and cut a new slot for the chainplate through the deck and fiberglass the old slott,which required that the spreaders now be swept back so the mast had a proper bend not inconsistent with the bias of the mainsail. I did that by cutting out angles in the spread roots so that the spreaders would sweep back at the proper angle and then everyone was happy. Of course, if you are racing one design, you cannot do this. The Ultimate 20's in last year's U20 Nationals, I think it was, had a group who decided to make up carbon spars for some of the boats while others remained with the same aluminum spars (original), but they didn't tell anyone and there was no adjustment in handicapping (and handicapping doesn't exist in one design). Well, essentially they made the aluminum spar boats obsolete and not competitive, but there was no alleged change to the class rules and some with aluminum spars showed up not knowing that they had to compete with carbon spared U-20's. Anyway, not nice. But, our Santana sailor friend probably isn't racing one design and so no worry. But, just saying, if his mast was swapped out and the design was not the same (you can have different sections, but it still has to be consistent with original), then he found problems similar to the Hake story, perhaps.
 
May 12, 2008
24
Santana 525 Bristol, PA Delaware River
RichH said:
John - exactly how far in from the rail is the chainplate located on this boat? I have located the plan and profile sketches for your boat .... but not enough detail of exactly 'how far in from the rail' the chainplate is located. I'll save any further comments until you advise. Approx. distances are ok. On the other boats, where is the genoa track and where is the chainplate .... how far 'in' from the rail?
This boat is VERY beamy for its length and that may be one of the items that may need a 'workaround', especially if the chainplate and the jib track and fairlead car is AT the rail.

Lemme know.

I live about 45 minutes from Bristol ..... perhaps I can stop by and do a 'look see' on my way to the Chesapeake. , etc. if the dimension info from you doesnt 'compute'.

;-)
Hi Rich,

The chain plates are about 12 inches from the rail. And even with each other (good story Barnacle Bill). I have 2 other boats like mine at my club as a reference both with the stock Kenyon masts and spreaders. I have identified my mast as a Dwyer. Changing the angle doesn't look possible with the way the tabs come out of the bracket.

Pictures: https://picasaweb.google.com/EEYC20...&authkey=Gv1sRgCJaxrtnV5Kb6VQ&feat=directlink

Where in PA are you? I live in Langhorne.

John
 

RichH

.
Feb 14, 2005
4,773
Tayana 37 cutter; I20/M20 SCOWS Worton Creek, MD
Here's a graphical analysis of a 525, using 'brochure' drawings.


First off, the 10-12° lines drawn from the tack will be the approx. sheeting angle for pointing with the jib in ~10kts., more open angle as the wind goes higher .... keeping the clew to these angles will result in the approximate best 'slot open' distance, hence pointing ability.

You'll also see immediately that the chainplate connection point is well outboard of the 10-12° line, also see that the 'aqua' on the profile sketch (looking at a jib in frontal profile) is also within the line directly from the chainplate to the mast (no spreader!)

What this means is that for pointing optimization that you cant carry a jib larger than about 105-110°; and, if any larger LP jib is used, the leech has to be cut with a large amount of 'hollow' so that it clears the spreader. Not to worry as a large LP genoa isnt going to be that effective in pointing, especially if its clew is outside that 10-12° line.

For racing, this means if you want to dominate the other two 525s in your fleet, youll have to change/peel to a larger genoa for downwind ... or simply fly a spinnaker if the local rules allow (for simplicity, a 'free flying', Ronstan type, spinnaker furler @ a cost of ~$300 would be 'the cats meow for downwind sailing).
For racing and for peeling/changing, Id opt for a dual groove 'tuff-luff'. A 'furler' would severely reduce the exposed luff area as well as %LP to 'fit'; but, if the other 2 boats are carrying their clew outboard of the 10-12° line they wont be able to point either, so a furler with genoa and a large %LP reduced so that the leech 'just hits' the spreader may still be a strategic advantage.

Since the shroud chainplate to mast line, even without a spreader, is well outside of that 10-12° line, sweeping the spreader further back or shortening the spreaders will not be of signficant value. .... using a smaller full hoist, deck sweeper, ~105±% LP is what is going to make this boat 'point' like a banshee.
Youll need both a pull-in barberhauler and an pull-out barberhauler to get the 'slot distance' correct (or secondary genoa track with a bridle between the secondary and primary genoa track). How to set: get the boat maximized for shape and trim with all tell tales flying perfectly, then slowly pull IN on the barberhauler while you watch the speedo (or better VMG on a GPS) for max. speed, then slightly ease. Totally ignore 'backwinding' when doing this barberhauler adjustment. When winds are 12+kts. then pull the barberhauler out while looking for max. speed. Once you get max. speed via best 'slot open adjustment' then you can slightly cup-up the leech on the mainsail a wee bit to help get the keel to lift and to POWER 'point' when needed. Setting the correct 'slot distance' will enhance the aerodynamic flow over 'both' sails.
For best course/leg to weather mark, do *search* for 'turbo sailing' on this forum. http://forums.sbo.sailboatowners.com/showthread.php?p=806425&highlight=turbo sailing - post #12

hope this helps. ;-)



BTW ... if thats your boat in the first 2 pics of the the above URL you posted ..... your boom aft end is drooping into the cockpit .... meaning that the mainsail isnt properly 'raised'. Go to: http://forums.sbo.sailboatowners.com/showthread.php?t=120970 to find out how to properly raise a dacron mainsail ... and set proper helm pressure at the same time.
 
Last edited:
May 12, 2008
24
Santana 525 Bristol, PA Delaware River
I spoke with Dwyer who made my mast and they are able to make a new bracket at the exact angle I need for it to be adjusted to put the spreader tips directly over the chain plates so this should help. I thank everyone for their comments and assistance. I just now need to figure out exactly hoe to come up with this angle to give them! Off to the boat I go!
 
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