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S&S Swan Maintenance - swan 37 double spreaders rig
07 February 2010 - 23:02
#1
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kamo
Join Date: 22 November 2008
Posts: 8

swan 37 double spreaders rig
Hi, I recently purchased a Swan 37(n 28, first name "Top Fit") which is now undergoing restoration. I have many questions for you and I will start from the mast. It is double spreaders rig version. I see on S&S sail plan (design n 2035) there are running backstay; are they optional? Were can you attach them on deck (no chain plates)?
Second question: I noticed a delamination below the bulkhead ahead the mast; it looks superficial (see fotos). Is this because of the movement (and load) of the mast without running shrauds? Someone has similar experiences? Do you think I can leave it and fix next season (I still never sail the boat an I would like to see what happens under load)?
Many thanks for any advice, best regards Federico

10 February 2010 - 08:26
#2
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the professor
Join Date: 02 January 2008
Posts: 1547

Dear Federico

Most 37:s do not have runners. Attachment points on the mast would also be required

Without runners mast compression is reduced, and the loads in the cracked area are smaller. It is likely there is some other reason for this problem.

It appears the cracks are not fresh, and you could well go sailing on short trips in moderate weather, and observe what happens.

It is recommended that the area is reinforced by extending the transverse floor right down to the bottom of the bilge, and taking care to connect the upper edge to the bulkhead. A small limber hole is needed at the bottom.

Kind regards

Lars
10 February 2010 - 23:45
#3
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kamo
Join Date: 22 November 2008
Posts: 8

Dear Lars,
thanks for your answer, I was really wait for it.

About runners I make a bit of confusion and I will try to by more exhaustive.

It is the two spreader tall rig version (I think higher mast and smaller section) and the mast come whit runners and their attachment points that looks original nautor made (isn’t it?).

To attach runners on deck, previous owner fixed two plates (one each side) a meter behind the in line whit mast chain plate.
I removed this custom plates for several reasons: the load was part transmitted on a sandwich deck, water passed and wet the sandwich, according to Stephens design they were to ahead, etc..

The question is: are runners structural for this kind of mast and rig?

Where is the correct place to fix them on deck? Can I use an existing point (tracks, eyebolt on wash-board) or I need to do it custom again?

Now I understand that when the mast is free to move and curve, compression is reduced.
My misconception was that movement of the mast in rough sea could produce a dynamic load that cracked the transverse floor.
I agree with you on haw to fix it. The bulkhead need to go to the floor and you explain how to glow it in a previous post.

I am still interested to know why crack happened and if anyone else has had the same problem.

Thanks to all and sorry for my english.

Regards, Federico

11 February 2010 - 18:02
#4
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the professor
Join Date: 02 January 2008
Posts: 1547

Dear Federico

Thank you for the information.

The picture shows that the runner attachment on the mast is original.

The attachment on deck should be on the rail, and preferably with the dead end and lead block separated, and the longitudinal position roughly as indicated on the sailplan.

If you could measure the mast cross section length and width and inform the dimensions it can be determined whether runners are needed in big waves or not.

The I-measurement is the same 46.25 ft for both the single and double spreader rigs

Kind regards

Lars
15 February 2010 - 23:24
#5
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kamo
Join Date: 22 November 2008
Posts: 8

Dear Lars,

Tanks for your advise,

The mast cross section length is 204mm and width 122mm. The thickness is 4mm.

It would be nice to know what kind of calculations you will do..

Regards Federico
16 February 2010 - 19:34
#6
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the professor
Join Date: 02 January 2008
Posts: 1547

Thank you for the measurements. This is the original section, and the runners are needed in big waves.

The stiffness of the mast is compared to the requirements for a mast without runners.

Lars
04 March 2011 - 18:07
#7
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kamo
Join Date: 22 November 2008
Posts: 8

The repair was made as suggested by Lars (thank you).
Now I do not see movements when pull the backstay..
Regards Federico
13 September 2012 - 23:58
#8
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mclarenr
Join Date: 03 December 2007
Posts: 10

Dear Federico

Thank you for the information.

The picture shows that the runner attachment on the mast is original.

The attachment on deck should be on the rail, and preferably with the dead end and lead block separated, and the longitudinal position roughly as indicated on the sailplan.

If you could measure the mast cross section length and width and inform the dimensions it can be determined whether runners are needed in big waves or not.

The I-measurement is the same 46.25 ft for both the single and double spreader rigs

Kind regards

Lars

Hi Lars and Federico,

My Dulcinea, Swan 37#17, has the double spreader mast and the same running backstay attachments shown in Federico's photo.  I have a padeye built into the rail just aft of the third stanchion as shown on the lines drawing.  However, I do not have any padeye forward of the stanchion.  Is the dead end of the runner attached to the base of the stanchion?  If not, what sort of padeye is recommended through the deck (not the rail, which would be most difficult for me to build)?  Thanks. 

--Richard McLaren

1970 S&S Swan 37 #17 Dulcinea
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