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TOPIC: Mk2 Centerboard sloppy fit

Mk2 Centerboard sloppy fit 5 years 11 months ago #645

  • Abitlight
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Hi All

I have recently aquired a mk2 and have sorted the basic niggles but the centreboard is a very slack fit in the box. I have had the board out, tidied it and the box up, new gasket etc. I need to add a bit of friction as it wobbles when right down and wont stay all the way down. I also think the slackness puts undue load on the pivot mounting arrangement especially when I am standing on the board :blush:

I have a few ideas but suspect someone has an elegent solution already

Paul
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Re: Mk2 Centerboard sloppy fit 5 years 11 months ago #646

  • Cirrus
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Hi

Not a major problem but still annoying. Best solution is to get some (very) cheap thin foam backed carpet. Rub the foam off and impact adhesive it to either one side of the plate or one side of the plate case. Both sides is likely to be too much. Alternative is 'jap tape' packing but I prefer the carpet solution. It also provides just the right amount of friction and also protects the board as well.

The Mk1/2 centreboard hanger is a bit of over-kill engineering wise but worth checking from time to time as well while you are messing about in that area.

Mike L.
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Re: Mk2 Centerboard sloppy fit 5 years 11 months ago #647

  • Myles Mence
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Paul

I had a similar problem on my Mk2 and discovered the sides of the box were not parallel in the vertical plane.

Having tidied up the box as you have done I masked up the section of the plate that is in the box when it is right down so that I could pour on a flow coat of epoxy to depth of 1-2 mm. Then cut back with wet and dry on a block with the boat on its side and kept offering up the plate; after a bit you get a snug fit.

Happily the box turned out to be wider at the top than the bottom and so the plate in effect would wedge itself down.

Myles
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Re: Mk2 Centerboard sloppy fit 5 years 11 months ago #648

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Mike, Myles

thanks for the replies.

I always wondered what jap tape was now i realise that another boat in the club is using it.
I think I'm tending towards the build up of epoxy, as ths carpet will tend to hold sand and will be abrasive in the long run.

Myles can you remember what product you were using as a flow coat? as I know you can get in a mess using the epoxy or polyester resin. I seem to remember polyester won't set up over epoxy or is that just gelcoat. Did you just build up the one side or equal amount on both side?
I will get the boat on its side and work out a suitable area to build up

many thanks
Paul
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Re: Mk2 Centerboard sloppy fit 5 years 11 months ago #649

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Hi

All boats prior to 747 will be in Polyester - those including 747 and since are in epoxy. In hindsight we could have or should have switched to Vinylester, a hybrid resin that is clearly superior to polyester and better in some ways than epoxy when the Mk3 came out. Anyway all later boats are and will remain in epoxy even though we don't exploit all its advantages to the full in the Blaze.

By way of a relevent update Cirrus is currently investing in new foil tooling for Blaze foils at some considerable expence. The new tooling is CNC cut from solid aluminium and should produce foils as good as you can get anywhere - i.e. exactly as originally designed and fully optimised. The rudder blade is also used by Icon as well as Blaze and the increased volume potential allowed us to make this significant jump. Earlier foils increasingly needed post moulding 'fairing' as the original GRP tooling progressively aged.

Mike L.
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Re: Mk2 Centerboard sloppy fit 5 years 11 months ago #650

  • Myles Mence
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I use SP 106, add some glass bubbles to thicken the mixture a bit and which is reasonably easy to cut back. You can buy a "handypack" with instructions and it is easy to use, the glass bubbles you buy separately. At the same time buy some microfibres which you add to make a glue - not for this job but for some time in the future - you will be pleased you did. (Microfibres give a hard finish and sanding takes a lot longer).

There is nothing to fear using epoxy on the centreboard. Cut the surface back beforehand and wipe with acetone to make sure the surface is clean. You will find the area to epoxy ie that which is in the plate case is surprisingly small. Apply the masking tape around the edge of the centreplate creating a wall to hold in the flow coat. Just pour on the mixed epoxy and help it spread on the level surface, it will find its own level. It will tend to combine with the tape in places which can be difficult to remove once set but a sharp stanley knife will assist. Only treat one side of the board at a time. Leave it to go off overnight, warmth helps.

Oh and buy the slow hardener - you get a choice - fast hardener will go off too quickly for this job.

Myles
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Re: Mk2 Centerboard sloppy fit 5 years 11 months ago #651

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Thanks for the info

I think I have some epoxy, microballoons and microfibers somewhere but no glass bubbles. I will get some bubbles as i don't want to be sanding forever.
I might take the board out to do the building up at home and then refit to do the cutting back on her side. That way I can get some heat on the board while curing as well.

many thanks
Paul
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Re: Mk2 Centerboard sloppy fit 5 years 11 months ago #652

  • Myles Mence
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OK you are familiar with the kit which is great and forgive me for being pedantic. For glass bubbles read microballoons but the former are white. Just one point which occurred to me last night in the bath - have a spirit level handy to level the plate before you pour on the flow coat. If the surface is not absolutely level you will have one area with plenty to sand back (tedious) and its opposite with nothing to sand back (tedious) as you will have to put on another coat.
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Re: Mk2 Centerboard sloppy fit 5 years 11 months ago #653

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Hi Myles

I appreciate the detail, it give me confidence that i am on the right track. I have some familarity with epoxy/glass work but as they say sometimes a little knowledege is a dangerous thing

Paul
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