Useful Snippets

Performance

The following is a note from our past Commodore in response to a query regarding performance,

In our club (Blackwater) a twin keeled Tomahawk PN1202 is rated marginally faster than a twin keeled Centaur PN1208. It is certainly faster than Alan Hill’s Sabre 27 at PN1237, but slower than a twin keeled Sadler 25 at PN1198. (The fin keeled Tomahawk is a very fast PN1063).   We only “race for fun” in Club Week, when Malibu, a twin keel, receives a club handicap of 1240. Other 25-footers also receive a generous rating because we are genuine cruising (as opposed to racing) boats, carrying full tanks of diesel (Malibu has 40 litres), water, second anchors, tool kits, stores, rubber dinghies etc.   If you want a 25 footer specifically for racing then go for one of the modern Beneteau or Jeanneau thoroughbred dinghies-with-lids !   At sea you need a boat with a bit of “bottom”. The Tomahawk’s ton-and-a-half of ballast helps her keep her way in a head sea.  Malibu has no difficulty in clawing off a lee shore in a F5 / F6, but above that she would be hard pressed.  Last year during Club Week racing we got hit by a 51 knot squall, followed by about five minutes of 40 knot wind blowing us into very shallow (4 feet !) water. We had two reefs in, with only half the genoa unfurled. Upwind progress was difficult. We started our 13.5hp Beta and motor-sailed to safety, retiring from the race along with the other cruisers in our vicinity. TOA members who race their Tomahawks in the IOW Round the Island Race do quite well. This year our Treasurer, Gordon Keyte (Nokomis) finished 138 out of an entry of 1770. (OK – it’s not amongst the silverware, but still not bad for a sixty mile race.)  If you want to find a useful (unofficial) list of Portsmouth Handicap ratings look at   www.byronsoftware.org.uk

Useful links

To start the ball rolling here are some suggestions (these are suppliers – I did the work myself !)

Malibu’s headlining : I obtained the foam-backed vinyl and adhesive from :         Hawke House Ltd,  E1 Heritage Business Park, Heritage Way, Gosport, PO12 4BG         02392 588588   www.hawkehouse.co.uk   Timber (4mm marine ply, over which I stretched the vinyl) I obtained from :         Robbins Timber, Brookgate, Ashton Vale Trading Estate, Bristol, BS3 2UN         0117 963 3136  www.robbins.co.uk Timber (iroko, cut to 11/4″ x 3/8″ battening) from :         All Oak & Hardwood, Brook Lane, Great Baddow, Chelmsford, CM2 7SX         01245 478747  www.alloak.co.uk Fibreglass supplies from :         CFS Fibreglass,  United Downs Industrial Park, Redruth, Cornwall, TR16 5HY         01209821028  www.cfsnet.co.uk Stainless steel screws and bolts from :           Sea Screw,  4 Churchdale Road, Eastbourne, East Sussex, BN22 8PS         01323 430294 www.sea-screw.comMalibu’s replacement windows  (6mm perspex, drilled & bevelled, £262.03 in 2006) came from :         Houdini Marine Windows Ltd, Hallmark Industrial Estate, Southminster, Essex, CM0 7EH         01621 773590  www.houdini-marine.co.uk I can recommend all these suppliers, who offered an efficient and helpful service.   Many thanks Ian – this is the sort of service I think we can usefully offer to TOA members (and it helps ourselves too). Do people think a comparison of insurance rates would similarly be useful.  I have just renewed Malibu’s insurance for next year :  Premium (with full no-claims bonus) £153.88 to cover : Hull, Gear, Engine & Equipment £14,000;  Dinghies (2) £400, Outboard engine £400; launching trolley £1,000). Kept on swinging mooring, April 1 to Oct 31. No racing. This is with Lloyd’s per Amlin through Nautical Insurance Services Ltd, Leigh-on-Sea, Essex, SS9 1SP,  01702 470811.

Rudder problems – a few words from Alan Hill

From: Alan and Jen <aljen@dsl.pipex.com> To: jengo@talk21.com Sent: Saturday, 28 November, 2009 20:01:12 Subject: Tomahawk rudders
Hello Gordon.  Re your editorial In The Tomahawk Nov., 316 ST STEEL was specified on the design of the rudders to Marcon . I  do believe that  whilst 316 was employed in the manufacture of the stock St steel of a lower grade was used in sheet form for the tangs, the processof welding to the stockof these differing materials plus the foam injected in the blade [quite a common undertaking in those days and most likely still occuring] oncethis becomes wet thro’ ingress of moisture via the entry point of the stock or pintle the result is fairly qiuck degregation of both the tangs and welds .I  do not know of any x ray techniques that are in existance and from years of surveying I would not tust any findings which they might show up.. The article in the bulletin is first class and a good step by step way of going about the task,   by doing so it puts ones mind at rest about this important part of the vessel. 

  Their are two things you can do which are easy to do without removing the rudder. 1. see if any rust is visable from any part of the blade .   2. Drill small hole at he lower end of the blade  say about 2 inches and see if rusty water emmits. 3.  Arange for sme one who is strong to hold the tiller to one side whilst you apply force in opposite direction to the blade, if you see any movement between the blade and stock you have an internal problem . Sometimes theirs no easy solution     

 All the best   Alan Hill.

Stability Rating  (via SailingNetworks.com)

I think Marcom’s ballast ratio figure of 46% for the Tomahawk is the nearest the class has to a Stability Rating. The other relevant statistics are the displacement (5,066lbs) and the ballast (2,360lbs).

Malibu was issued with a RORC certificate in 2000 which gives her DLR (displacement / length ratio) at 280. This is high compared with modern racing cruisers, but is what makes our little boats so seaworthy. The race Mike is planning to do may limit entries from boats with a high DLR because they may be deemed too slow. SailingNetworks.com   Propellor sizing I know of a couple of websites that give a simple calculator to work out optimum sizing. http://www.electricboats.co.uk/surfprop/ There are other prop calculators on the web, that can be used to run a check eg www.castlemarine.co.uk

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