Converting my Nordship808 to JR

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  • 05 Jun 2025 13:37
    Reply # 13506991 on 13481250

    Thank you, Thomas.  I really appreciate the information.  It is good for me to see that for a very similar JR conversion, my mast design calculations align right with yours.  That is a relief!

    Regarding the mast step and partners I'm of the same mind as you. (I see your edited comments now).  I am completely aligned with the approach you describe, and it all makes perfect sense. I do have access to CNC, which could save a lot of time in fabricating the plywood components. I'm going to have a a friend who is a structural engineer look at the step and partners design, but my Alberg 30 is a stout old boat, and I'm confident it can support the load.

    Because I have have a friend that owns a metal working shop, I am considering sizing the opening in partners and step to receive a stainless or aluminum flanged tube within the glassed plywood.  The deck piece would be flanged and through bolted through the partners,  and the mast step piece would be flanged to lag bolt into the mast step.  This would allow me to secure the mast to the keel step piece with a large through-bolt.

    This is very similar to Arne's approach in his February 2018 article, just I'd like to apply the same idea to the mast step (attached).

    Thanks, again. And best of luck,

    Joe

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    Last modified: 05 Jun 2025 14:00 | Anonymous member
  • 04 Jun 2025 15:55
    Reply # 13506635 on 13481250

    Hello Joseph,

    Sorry for my late answer, but I enjoyed sailing in Croatia with a conventional sailboat;-)

    I do not feel competent enough to give any advice, my method is try and error, when in doubt: Add one layer...

    I will try to write something about my ongoing conversion in the boat shed, as Paul asked me to do so. Today I realized that the mast I purchased (tempered flag pole) was slightly damaged by a visitor with his car. Not to take any risk, I will have to buy a new one, which may be thicker than my 150mm/5mm flagpole. Besides the cost I already had this in mind and I am currently laminating in a 200mm/5mm sleeve, that would allow to house a mast of up to 170mm diam. Still I have not decided yet, if  I will have a mast laying device, which would ease any futher alterations concerning the rigging.

    As basic material I used 16mm AW100 plywood for the basement and the partners, , the partner rings I screwed with inox screws and glued them together from half rings, which is a lot of additional labour. If you have someone nearby to cut out the rings f.e. with a CNC machine, that would probably save quite some hours of effort. also a cone could be easily shaped, which eases the later laminating.

    As I could place my new mast foreward enough to save the front hatch, I also used the front hatch support and reinforced it by 3 layers of plywood.

    As lateral reinforcement for the deck partners I glued in two "beams" of plywood 100 X 16 which I reinforced by another layer of 70X16 plywood. Laminating the whole construction with 5 layers of 450gr/m² triaxial glass fabrice. The same I did from the lower deck partner to the bow (rather to the anchor chest).

    On deck 4 layers of plywood make the base for the upper partner, laminated with 10 layers of both bidirectional and triaxial fabrice.

    The keel bottom is made of 4 layers plywood, the most difficult for me was to get the bottom partner half way horizontal, though my 200mm/5mm sleeve will allow some adjustment play to get the mast straight.




    Last modified: 05 Jun 2025 08:50 | Anonymous member
  • 28 May 2025 19:00
    Reply # 13504060 on 13481250

    Thomas, 

    Thank you so much for sharing your progress.  I am planning a JR conversion on my Alberg 30, which is very similar to yours in mast and rig sizing. 

    Can you tell me more about how you developed the design for your mast partners? I was thinking about taking the same approach as you, but also adding a transverse deck beam fore and aft of the mast, connected to the mast partners on the under side of the deck. I'm not sure if this additional step is necessary. 

    Thank you, again, for sharing and I look forward to any information you could share. 

    Cheers,

    Joe

  • 26 May 2025 13:00
    Reply # 13503249 on 13481250

    Slowliness is Holyness

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  • 03 May 2025 07:37
    Reply # 13494822 on 13481250

    Thank You Graham, I will have to consider wedges.

    Thomas 

    Last modified: 03 May 2025 07:38 | Anonymous member
  • 03 May 2025 06:45
    Reply # 13494817 on 13488175

    Today the first step (the mast step) was laminated. 3 layers of plywood 16mm (A100) glewed in the front section and laminated with 2 layers of 300gr roving + 1 layer of 450gr roving. Will be reinforced when laminating the partner for the sleeve in the correct angle.

    I wonder if I should put a metal plate to the bottom, or if epoxy laminate will be strong enough to withstand the hammering of the mast. 

    I decided to work with a 200/5mm aluminum tube as sleeve for the mast.

    Is there any experience how to pull the mast out once it should be filled with moulding PU in the sleeve, any separator advice? Or rather use wedges?

    More questions to arise...

    From memory, when David Tyler decided to remove the mizzen mast from Tystie, which had been held in place with Spartite, he ended up cutting the mast off at deck level, as it wouldn't budge.  I have heard that if you have tapered partners, and use a release agent, or even a plastic film, you should be able to knock it out from below with a rubber mallet.  If you are going to place your mast inside that alloy sleeve, then I suggest that, if you want to remove it again, you'd be better off using softwood wedges.  On Arion, I used western red cedar wedges and it proved to be an ideal material.
    Last modified: 03 May 2025 06:46 | Anonymous member
  • 02 May 2025 15:44
    Reply # 13494513 on 13481250

    I hope, my ship will be faster than my progress

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  • 21 Apr 2025 16:00
    Reply # 13490056 on 13481250

    Today first try to fit in the sleeve

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    Last modified: 21 Apr 2025 19:14 | Anonymous member
  • 19 Apr 2025 15:22
    Reply # 13489462 on 13481250

    Proceeding. 


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  • 16 Apr 2025 17:35
    Reply # 13488175 on 13481250

    Today the first step (the mast step) was laminated. 3 layers of plywood 16mm (A100) glewed in the front section and laminated with 2 layers of 300gr roving + 1 layer of 450gr roving. Will be reinforced when laminating the partner for the sleeve in the correct angle.

    I wonder if I should put a metal plate to the bottom, or if epoxy laminate will be strong enough to withstand the hammering of the mast. 

    I decided to work with a 200/5mm aluminum tube as sleeve for the mast.

    Is there any experience how to pull the mast out once it should be filled with moulding PU in the sleeve, any separator advice? Or rather use wedges?

    More questions to arise...

    1 file
    Last modified: 16 Apr 2025 17:41 | Anonymous member
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