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S&S Swan Maintenance - Swan 37 Deck elevation.
22 November 2019 - 11:06
#1
Join Date: 05 February 2012
Posts: 21

Swan 37 Deck elevation.

Dear professor, 

On the pictures you can see conciderate deck elevation near the chainplates on our Swan 37 Tarot. I know that you propose to have the inner end of the chainplate knee, lengthened until it sits under the coachroof coaming. But as you can see on the photos this would mean that only a small reïnforced pôlyester tip would end up under the coachroof coaming. Will this be enough to withstand the upword force on the knees?

So, what can you advise on the idea of putting in new stainless steel chainplates on both sides of the knee, but make them end under the coachroof coaming? To spread the load of these tips we can have a narrow strip of stainless lengthwise with the coaming where the two chainplate tips are touching.

On top of that would you advice to strengthen the underside of the chainplatekees with polyester matting as you have suggested in a previous drawing? 

 

Many thanks for your highly respected advise!

 

Geert

 

 

Deck elevation as on both sides

Chainplate knee

Tip of chainplate knee

22 November 2019 - 18:58
#2
Join Date: 02 January 2008
Posts: 1547

Dear Geert

Thank you for your message with photos.
You have an additional screw-in fitting at the inner end of the chainplate knee, assume this is a high aspect jib sheeting point, and the sheet loads there are high. 
It would be advisable to add a strong attachment also for the sheeting point. If you extend the vertical steel parts so they end onto a longitudinal steel beam as suggested, you would need to add a triangular horizontal plate which takes the screw-in fitting screws, and has a vertical support plate near its forward edge, also terminating on the same longitudinal beam. I better make a sketch. 
This addition will not fit inside the present chainplate cover, be prepared for modifications.
The GRP knees do not need additional strengthening if the steel parts are dimensioned to take all the loads
Kind regards

 

Lars

22 November 2019 - 20:32
#3
Join Date: 11 November 2017
Posts: 25

#12 Pohjanneito is reinforced with steel plates. I will upload photos tomorrow here.

 

JereQ

23 November 2019 - 10:14
#4
Join Date: 05 February 2012
Posts: 21

Thank you professor, but a drawing of your explanation would be practical.

Looking forward!! 

Geert

24 November 2019 - 12:01
#5
Join Date: 02 January 2008
Posts: 1547

Dear Geert

Here a proposal for your consideration
Looking from below, the blue lines are 6 mm steel plates on edge, and there is a triangular horizontal cover plus an outside flange against the deck for receiving the through deck bolts.The position of the fourth bolt on the other side of the knee is not visible, but a similar arrangement with one vertical strip and a horizontal flange could perhaps be used.
The plates terminate at the longitudinal support bearing against the underside of the coaming.
The suggestion is to to bolt the outboard end of the vertical plates to the existiing chainplate steel brackets using the existing bolts, which probably needs to be longer. 
The bolt holes in the plates need to be drilled exactly, so the plates will distribute  the outboard end loads to the brackets. 
If there is play between the inboard end horizontal support and the coamoing, a filler piece should be put in to make the connection tight, this will distribute the inboard end loads to the coaming. 
How does this sound? 
Kind regards
Lars

24 November 2019 - 20:45
#6
Join Date: 11 November 2017
Posts: 25

Here is a image from Pohjanneito #12

 

JereQ

25 November 2019 - 11:19
#7
Join Date: 05 February 2012
Posts: 21

Tnx professor, will draw it out on place now.

 

25 November 2019 - 11:20
#8
Join Date: 05 February 2012
Posts: 21

Tnx JereQ!!! Did it stop the decklifting close to the coachroof?

Geert

26 November 2019 - 19:52
#9
Join Date: 11 November 2017
Posts: 25

Hi, 

I have never had this kind of problem. The previous owner fixed the deck crack when a new teak deck was installed.

JereQ

10 December 2019 - 10:05
#10
Join Date: 05 February 2012
Posts: 21

Dear Professor,

Here some photo's of the new chainplates for Tarot. They have been remade, longer on the tip, reaching under the cabinsides and finalised with a massive plate of about 30 x 15 cm length wise under the ceiling to spread the loads under above the chainplate tops. The chainplate covers are being adapted now and will be added soon!

We hope to have no more problems now with decklifting in this area.

Thanks for your help, as always!

Geert

10 December 2019 - 16:05
#11
Join Date: 30 January 2007
Posts: 446

Good job, Tarot.

Just a couple of questions: which is the thickness of the 30x15 plate? I assume of course that it is stainless steel and was laid flat on the lower surface of the deck; was it glued or covered with laminate?

Another question regards the upper side of deck; how did you treat the bulging?

Daniel, 411/004 Luna Menguante

11 December 2019 - 16:49
#12
Join Date: 05 February 2012
Posts: 21

Hoi Daniel, the horizontal plate is about 30 x 15 cm indeed and 10 mm thick.

She is glued to the underside and fixed with the bolts of the high aspect jib sheeting point. So immovable and taking the load of the chainplate tips.This plate sits between the deck and under the coachroof coaming, and the chainplates.

Invisible from the inside as covered by the ceilingplates and the adapted chainplate covers.

Geert

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