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hello all

ive been absolutely flat out.finally got a bit of time to get back to my boat.

thanks to those who have taken the time to reply.

Martin- what a great site you have lots of info. i'm very interested in your composite beams, does this let you do away with the dolphin striker?

Freedom thanks for the compliment on boat looks

ScottiE any info will be appreciated

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would anybody have any photos (close ups) of mast bases used on Tennant style cats.

does non rotating make any difference to the loading on the mast base?

 

Ken, for what it's worth, here are pics of the mast base on my Dakota 33 (Pilkington-built, exported to the U.S.)

 

There is a chrome plated bronze hemisphere that is not shown in the photos. It is fitted flat to the bottom of the mast. The curved part fits into the delrin bearing. You can see the "boot" sitting off to the left. The entire step is welded to a dolphin striker strut which goes through the crossbeam.

2010-06-30_12-39-41__0110.jpg

2010-06-29_18-22-16_0670503725_1515.jpg

Mast rotation hardware.jpg

Dolphin striker and engines nacells.jpg

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Martin- what a great site you have lots of info. i'm very interested in your composite beams, does this let you do away with the dolphin striker?

The composite beams started out with a composite dolphin striker. We designed and built them because the alu beams were not up to the job -- wracking while sailng in waves bent the fore beam. It happened twice despite beafing up that beam after the first time. Later I came in contact with a Belgian Spyder owner who broke his fore beam and an American whose dolphin striker ripped out of the main beam. Not fun but it was this we feared would happen when we saw the drawings. Hence, the change in dolphin striker design.

 

The the job market made me move from my native Gothenburg to Stockholm and the boat ended up on a mooring rather than in a marina berth. I found the dolphin striker sometimes 'interacted' with the mooring in an unfavourable way and it had always been a bit of an occupier of much needed space on the trailer. Eventually I removed it and added a fair ammount of unidirectional carbon to the mast beam -- a net weight gain of about 1 kg if memory serves.

 

So, yes, no dolpin striker but not from the outset.

 

Added bonus: you actually feel a bit protected from the elements by the mast beam despite it only being 35 cm deep.

 

/Martin

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thanks again for the replies.

 

myosys -

i assume the dolphin striker floats up and down through the beam.

does the beam have anything welded into it to keep water from entering the boat?

are the stainless plates top and bottom of the beam to locate the dolphin striker and stop wear on the beam?

i see some "rope" from the bottom of the dolphin striker to the intermediate beam, were you having problems with the striker moving around?

 

martin-

i could be very tempted to go with bigger(read higher ) composite beams a bit further into the future. the weather protection is important.

i'll get this problem sorted first

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i assume the dolphin striker floats up and down through the beam.

does the beam have anything welded into it to keep water from entering the boat?

are the stainless plates top and bottom of the beam to locate the dolphin striker and stop wear on the beam?

i see some "rope" from the bottom of the dolphin striker to the intermediate beam, were you having problems with the striker moving around?

Hey kda,

 

Yes, the dolphin striker, which goes through the beam and is welded to the mast step, is free to move up and down.

The beam itself inserts into a socket laminated into the hull. I've attached a photo showing how far the socket goes into the boat. It is integral to the bulkhead.

 

Yeah, I think the stainless plate performs a bunch of functions; wear, centering, and strengthening.

 

The rope is actually a stainless wire with a turnbuckle. According to the importer, Pilkington built the boat with this to stop the beam from rotating when "under extreme load." That's never happened and we're really had the boat in some hairy stuff. I've since replaced it with dyneema. It would take some load I suppose, since the mast crossbeam is elliptical in profile, so if it rotated you could imagine what would be happening to the hull!

2007-01-06_15-23-40_0420209507_8037.jpg

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again thanks for the replies.

 

ScottiE and myosys the plans and pictures look to be what i will have to get organised.

if anything else comes up please share it.

 

nice looking interiors on the boats. are they finished in gloss?

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Can’t take credit for the interior of mine - superb finish by the original builder. They used POR15 and brushed it on by hand - not that you would know - he’s a panel beater by trade so that’s why! It’s realy hard stuff and doesn’t chip.

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snap - your boards are quite a bit more vertical than mine

 

When I haul the boat (it's autumn here in Connecticut, USA), I'll measure the angle and let you know. Interesting...

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