Mast Rake for a Nethercott One Design

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Southpaw
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Mast Rake for a Nethercott One Design

Post by Southpaw » Sun May 02, 2010 1:28 pm

I have a Nethercott One Design built by Rob Michael.

What mast rake is considered best for the craft. Put another way if I were to hang a plumbline from the top of the mast how far from the mast would the plumb be at the foot of the mast.

Regards


Peter GBR 245.

mikeewart
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Re: Mast Rake for a Nethercott One Design

Post by mikeewart » Sun May 02, 2010 4:40 pm

Hi I have a Nethercott and can measure the distabce from top of mast to stern tomorrow if you want, I have carbon mast it might be different for a tin mast

Southpaw
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Re: Mast Rake for a Nethercott One Design

Post by Southpaw » Sun May 02, 2010 4:58 pm

Great, my mast in carbon fibre also.

Your help would be most appreciated.

Regards

Peter

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Christian AUS
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Re: Mast Rake for a Nethercott One Design

Post by Christian AUS » Sun May 02, 2010 8:05 pm

Hi,
Bear in mind that Nethercotts can be subtly different to each other (http://www.internationalcanoe.yachting. ... s/11863/0/), so a plumb line measurement to the stern may be very different from boat to boat. A better method is setting the boat up level and then suspending a string from the main halyard to a set point down from the black band on each mast). Add a weight to the string, and then measure the distance between the string and the mast at the agreed point. This will give you a more accurate idea of mastrake. Ideally do this next to another boat.

Rob
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Re: Mast Rake for a Nethercott One Design

Post by Rob » Mon May 03, 2010 9:06 am

Depending on the age of the boat & what the owners requirments were when it was first built, the mast position from the bow might be in varying positions from around 1850 to 2050 so a mast tip to transom measurment from other boats is no good here unless your mast step is in the exact same place. Rake adjustment will also depend on if it has fixed shrouds as on most AC's or adjustable ones as on most IC's. If its an IC then you will probably have adjustable shrouds mainly to let the leeward shroud off down wind to allow the boom to square off as far as possible. AC's usually have fixed shrouds with adjustment plates that allow rake adjustment before you go afloat depending on wind conditions. Usually as it blows more &/or you need to de power the rig, you start increasing the amount of mast rake which reduces the affect the spreaders have to hold the centre of the mast straight, opens the leech more & moves the centre of effort aft.
A good starting point though for your rig for light to moderate winds & you need as much power from the rig as you can get is to start with the rig dead upright relative to the waterline. Now a good method of setting your boat up on dry land is finding a bit of dead flat ground first, set the bow up on its launching trolley so that the distance from the ground to the underside of the transom on the keel line is the same dimension as from the ground to the keel line approx a foot back from the bow. Using a bubble level, you can set the mast up vertically to the ground. Make sure you have the full rig tension on when you set the mast up.
Now sail the boat flat & see if you have any excess weather or lee helm. If the helm feels fairly neutral then you can now check the adjustment of the spreader rake & length to improve the shape of the sail if its too full or too flat. The longer the spreader, the more affect they will have (average length approx 300mm long) & the more rake you put on the tips, the more you will pre bend the mast to depower the sail. There are so many options of mast & sail combinations & also their condition that this can only be an initial guide line & starting point to setting up the mast. Time on the water will give you more idea of how much rake you will need & to suit your sails & wind condition. Happy tuning.

mikeewart
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Re: Mast Rake for a Nethercott One Design

Post by mikeewart » Mon May 03, 2010 3:19 pm

Hi I measured my mast head to stern but from reading Robs post this measurement is no use to you, so I wont give it, having read Robs post I am going to check my set up as he says and see what difference there is
regards Mike GBR250

Southpaw
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Re: Mast Rake for a Nethercott One Design

Post by Southpaw » Mon May 03, 2010 7:50 pm

Thanks for all the infomation, particulary Rob's.

Looks like I have some work ahead of me to tune the boat. If I make a complete hash of the set up then hopefully someone will help me correct matters the next time I sail against any Canoes.

Thank again.

Peter

michael Brigg
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Re: Mast Rake for a Nethercott One Design

Post by michael Brigg » Thu May 13, 2010 6:01 pm

Just for interest really. My newly aquired K101 has been in Hibernation since 1970, and has a Gold Proctor ("C" I think.) It is a rotating mast, and has no spreaders. It is INCREDIBLY heavy and its CG is about 3m above deck level!

Is it even worth tuning?

My real concern when I get round to using it is the destabilizing influence the weight might have, and for that matter, bouyancy. I think this mast will have a powerful desire to invert yhe hull if I fall in.

When I start learning the ropes, should I attach a mast head bouyancy until I can sail more than 100m without a capsize?! :?
Michael Brigg

K102 "Torment." Cold moulded Nethercott
K203 "Moonshadow" Carbon "Pyranha" Nethercott (Spare boat. Needs a polish)

colinbrown
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Re: Mast Rake for a Nethercott One Design

Post by colinbrown » Thu May 13, 2010 7:35 pm

I have always used a plum bob hung from the main halyard to determine mast rake. In light winds I go for about 100mm, and increase this to 300-400mm in windy stuff. You will need to adjust the jib clew position.

jimc
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Re: Mast Rake for a Nethercott One Design

Post by jimc » Thu May 13, 2010 11:41 pm

michael Brigg wrote:When I start learning the ropes, should I attach a mast head bouyancy until I can sail more than 100m without a capsize?! :?
Consider what happens when you lose contact with the boat in a capsize (remarkably easy to do with a Canoe), and your boat is floating high with the plank acting as a sail. In a reasonable breeze the boat will be blown downwind faster than you can swim in westsuit, buoyancy aid and gear (trust me on this!): only if she inverts will you be able to catch up.

cc284
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Re: Mast Rake for a Nethercott One Design

Post by cc284 » Fri May 14, 2010 11:15 am

colinbrown wrote:I have always used a plum bob hung from the main halyard to determine mast rake. In light winds I go for about 100mm, and increase this to 300-400mm in windy stuff. You will need to adjust the jib clew position.
I need to use more rake when it's breezy!! Very interesting that you have actually taken this figure Colin, we should try and collect more data like this. Colin, where do you measure to - goose neck?
GBR 284 (AC) - 'Outlaw'

Southpaw
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Re: Mast Rake for a Nethercott One Design

Post by Southpaw » Sun May 16, 2010 3:59 pm

Colin thank you for your comments, I now have a good place to start from.

I agree it would be useful if this data could be collected but the measuring points would have to be standardised, eg Gooseneck or foot of mast.

Southpaw

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