Stiffening up a Mark I

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MelF
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Stiffening up a Mark I

Postby MelF » Sun Sep 17, 2017 2:58 pm

Hi all,
Hope life on the water is treating you well. Summer is finally in sight! :-)
Question for the Careel brains trust please.
What would be the easiest way to increase the stability of a Mark I - to improve self righting ability?
Lead on the cabin floor either side of the keel box ok? Low enough?
How easy is it to remove the keel and beef it up?
Thanks in advance.
Mel
Cal 14 'Charlie'
Gippsland

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maxm
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Re: Stiffening up a Mark I

Postby maxm » Sun Sep 17, 2017 7:59 pm

I did do a lot of thinking on the keel thing Mel but the problem is there isn't much room in the keel case. The only solution I could come up with (bonding lead flashing to the keel somehow) didn't really add as much as I'd hoped and that's starting with a lightweight keel. Others more expert may come up with better solutions like maybe some kind of cast keel. Lead under the cabin sole is probably the easiest solution. Also in the locker where the toilet usually goes. If you want to try it out without the expense of buying lead, why not try sand?

Mind you, this could put undue pressure on the hull and skeg during towing so it may not be such a great idea for the life of the boat.
Max
C22/54 "Katrina II"
Mitsubishi PC Challenger auto

"It could easily be accomplished viz a coppuder"
(Dr Strangelove)

MelF
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Re: Stiffening up a Mark I

Postby MelF » Mon Sep 18, 2017 12:28 pm

Thanks Max, all very good points to consider!
Cal 14 'Charlie'
Gippsland

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byrdsworth
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Re: Stiffening up a Mark I

Postby byrdsworth » Mon Sep 18, 2017 7:09 pm

Mel ... it depends on which mk1 you may have ..
a real early one will have the light 65kg keel
the later mk1's had a heavier keel ... my 1st careel 18 was #4 .. light keel ... I really liked the way she sailed ... more dinghy like I guess
but by no means scary ...

Now i have a mk3 which is heavier all round ... keel is way heavier as well as the boat itself is a lot heavier too
still getting used to the boat ... definitely less lively ...

Still miss the old mk1 ...

Cheers
Byrds
C18 #457 "Skye Mist"

MelF
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Re: Stiffening up a Mark I

Postby MelF » Tue Sep 19, 2017 8:33 am

Cheers Byrds,
Great to have the perspective of both from a sailing point of view, thank you!
Mel
Cal 14 'Charlie'
Gippsland

don47
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Re: Stiffening up a Mark I

Postby don47 » Wed Sep 20, 2017 7:57 am

Mel,, This is such an interesting subject & one that I haven't got near the time at present to go into as far to busy with C/ship matter at Wangi but, a few years back now I advised Mr trotter of a good way of beefing up his CB (keel) in a MK1. He had case probs at the time & so decided to address both matters on the same occasion.
The beefing up aids & gives the boat so much greater everything over & above the old standard rough blown out with torch 12-13mm flat plate that was simply then galvanised.
Paul wrote down much of his works in Technical Articles on this site under 'Trotter keel case Replacement & shaping of Centre Board".
It is a lot of work & if you're not at all handy it will be exxy to have someone do the job for you but, by following or performing the process you'll increase for eg. the 64kg weight of the thin board to approx. 75kgs if you absolutely fill the 25mm wide case & its all now down low weight (under the boat) plus far better shaped than from when manufactured which quite frankly was or is a joke.
Another thing one could do is replace the now light weight 12-13mm CB with a 20mm one. Many have done this & as pointed out by Birdie some of the later mk1's were released with the bigger which in my opinion is the best general weighted board for any C18 at 100kg plus a bit. Again a number were simply blown out with a torch & gal'd but many ended up being shaped & re-gal'd by certainly at least keen owners.
I've spoken to number of now & previous Careel racers/owners about this that to do with CB's.
One particular fella who had raced /cruised 18's for many years said that he believed the best overall weighted board for any 18 was between 100-120 kgs. His last boat did actually have the bigger cast job in it however & so he would have appreciated lighter.
The cast 186kg installed in later boats with the bigger slot of course, is simply to heavy for the boats general purposes. I asked Dave Rose directly once,, why did you make those CB's with so much weight. His basic answer was that the foundary people had to pour & mould it that size otherwise it might not last due to brittleness.
Certainly, I agree that the bigger cast job takes the boat into a yacht type feel rather than the dinghy !
Don.

MelF
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Re: Stiffening up a Mark I

Postby MelF » Wed Sep 20, 2017 12:49 pm

Thanks so much Don, very interesting.
I will look for and read Paul's notes.
Have a great season at Wangi!
Mel
Cal 14 'Charlie'
Gippsland

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paul trotter
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Re: Stiffening up a Mark I

Postby paul trotter » Thu Oct 19, 2017 8:06 pm

Mel,

Don is on the money with his advice but it all depends on your objectives.

A fast boat is going to be a light boat with a magnificently shaped centreboard. Wyuna became a super light fast boat and pointed brilliantly after the work.

But I live up on the northern part of Moreton Bay and its a dangerous part of bay with big fetch and currents. I upgraded to a Mark 3 with the big hefty 186kg plate. The boat keeps flat and is not nearly as tender making sailing solo so much more relaxing in big seas and air but.....she is slower than Wyuna. That said Mr Cook came second on scratch in this years Nats with a big CB.

So it depends what you are trying to acheive!
Paul Trotter
Nellie C18/472
Vice Commodore North CCYA

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maxm
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Re: Stiffening up a Mark I

Postby maxm » Fri Oct 20, 2017 6:11 am

Guys,

I think you're missing the point - Mel was asking about stiffening a Mk I, not making one lighter or faster or pointier. I assume she'd like it to be less tender. So how does she do this (and no Paul, buying a Mk III doesn't really count as an answer) :lol:
Max
C22/54 "Katrina II"
Mitsubishi PC Challenger auto

"It could easily be accomplished viz a coppuder"
(Dr Strangelove)

don47
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Re: Stiffening up a Mark I

Postby don47 » Fri Oct 20, 2017 10:01 am

Actually Max, read Mel's first post. She is talking about righting & stability,, which can only be gained by having greater weight in the bottom of the boat & there is no greater place for weight down low in a boat than in the CB or keel. Yes, sure extra weight laid & fastened down to centreline of boat internally will assist but, be careful of location for balance reasons however around the areas of CB/keel case & bit forward thereof should be ok & even in the old loo position. Trial some weight beforehand Mel, move it around somewhat whilst out on the water. Eskies with some sand or bottled water in them might be good instead of beer & ice however be cautious as you don't want damage because of excessive long term or loose weight whilst perhaps on water or road.
Personally, if I were Mel & wanted extra weight for righting & stability plus being reasonably care free & not have to worry about to much in the future then I'd probably throw a gal'd 20mm board into it for greatest weight gain plus a 19mm stainless pin for greater longevity & strength. If you do want a bit better performance from the boat, then that board before being gal'd & installing Mel needs to be shaped but, realise you'll loose some weight (maybe 20-30%) in that process depending how great the amount of shaping. Note that the slot in a mk1 is something like 24-25mm max.

Stiffening up a boat actually refers to how strong or weak the hull itself is, does it flex or not.
We all know that the mk1 hull (especially early boats) were certainly not built near as stiff a hull as the mk2 or mk3 but, some definitely appear to be stiffer than others because of who sprayed them up on what day probably. The later mk3 particularly is constructed quite differently with extra ply & fg (thicker) chop strand. Hence the greater hull weight/s of those mks!
If you wanted to stiffen up the hull/deck/seat areas of a mk1 or other then quite frankly I'd be probably glassing in where appropriate either timber, alloy or other suitable material stringers or if you like, call them ribs. Depending on where located your width of stringer/rib may vary somewhat as required. This is in no way as hard a job as it sounds but, needs to be done in a professional manner for the obvious reasons. Simply prepare properly the site & fg glue the cut to length & perhaps shaped stringer/rib into place under for example the fore deck if it appears bit soft to walk on. Do the same under seats or for the hull. All should be fitted & glassed into place quite easily inside the boat plus out of sight.
Don.


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