Building Paterson 8 in Dubai

[admin]

In Primal I changed from an unsupported gunwhale step down into the cockpit to having the cockpit deck flush with the inner gunwahle, it made the boat much easier to sail, I had a greater range of positions that I could stand and balance in the boat and it reduced the number of steps needed to tack.

It is also a smaller number of steps to build if the gunwales are level and should be stronger and lighter.

The hull is probably only 1m wide at it's widest point how far from the water can the centerboard be?

[Graham Bridle]

Doug,

I have some good photos of my boat in build that might help you, you can download them http://www.langhambull.com/riotvan.zip - in a hurry right now but will try to tell you more about which bits are right/wrong soon !

Graham

[daryl_wilkinson]

I have a low floor. 80mm @ transom / 200mm @ case / 260mm @ stem. With the low floor you'll need an extra bulkhead. Something that I designed my boat to have and Mike left out resulting in having to take the floor out and put back in the bulkhead. Due to floor flex and topside / gunwale flex. I also have a half deck / mast gate with a little extra bounancy coming from my gunwale height main bulkheads. They curved down in an arch to meet the floor from the gunwales. The cockpit side of the mast gate / half deck bulkhead should also be curved to reduce any point loading where the loads meet at the mast gate. This wasn't built with a curve as I had intended and as a consequence a remedial curved space frame has had to be put in under the half deck. The intention was a compromise to create a boat which floated low after a capsize, was stable after righting and gave the helm a good sitting in position downwind and allowed for a lower boom. ( my boat is also designed to be hiked with wide wings so this low floor should also make coming in from sitting easier ). And took the rig loads from my narrow shroud base. It's not exactly how I wanted it, but I should have built it myself if I wanted that, shouldn't I ? 

[doug1720]

Hi, recovering from a night out at the yacht club on the beach!  I hope everyone had a good time?

I have decided to go for a hybrid solution, so not full gunwhale to gunwhale but also neither a low false floor.  I will see how it goes.

I weighed the hull and around 20kg.

Thanks,

Doug

[Banshee Ambulance]

Hi, recovering from a night out at the yacht club on the beach!  I hope everyone had a good time?

I have decided to go for a hybrid solution, so not full gunwhale to gunwhale but also neither a low false floor.  I will see how it goes.

I weighed the hull and around 20kg.

Thanks,

Doug

Can you elaborate on this any further? Or give a diagram? I would be interested to see what you are planning.

[admin]

Hi Doug,

You can see in the purple picture the slightly recessed deck that I had, the problems with this were that I could not stand with both feet on the inner gunwhale and balance, so that meant that my in boat standing position was closer to the centerline, this gave problems with roll tacks and prestart manoeuvring. so after the deck was damaged on the rocks I decided to rebuild it a bit flatter and I was surprised how much easier the boat was to tack after the modification. I used one less step in each tack and was more balanced during the whole manuver. Ergonomically I found the flater cockpit much better.
Original setup

during modification.


When modifying I cut off a strip of hull the length of the cockpit that had been reinforced by adding an extra strip of foam and then a few layers of carbon over the top to take the punishment of being stood on and the two strips weighed in at 800g although they had absorbed some water where the foam had disbonded due to sailing abuse.

[daryl_wilkinson]

To be fair Phil... you are not the normal sized Cherub crew i.e massive!  . So the situation you describe may not be suffered by everyone. Just something for Doug to consider when weighing up the pros and cons.

[Phil Alderson]

To be fair Phil... you are not the normal sized Cherub crew i.e massive!  . So the situation you describe may not be suffered by everyone. Just something for Doug to consider when weighing up the pros and cons.

I am 6ft 3 and move about the boat like a small elephant so perhaps not so relevant to anyone else's sailing technique, however I have sailed the same boat with two different cockpit layouts and was surprised how big a difference it made, my comments were based on my sailing experience which is all I can use.

If I were building another boat i know what I would do.

[phil_kirk]

Doug  try to imagine how you go across the boat during a tack. Where you might put your feet and what angle of heel the boat may be at.  Also consider the distance between foot steps. This will depend on weather you have a short or long stride.

We put kick bars either out board of the spinnaker sock because without them we thought Sarah may struggle to get across the boat if we got a tack a little wrong.

It's a balance of structures; ergonomics; weight and static stability.

Our hull weighed 23kgs with the deck on and aft beams.

The spine and bulkheads weighed 2kgs.

[andy_paterson]

What's happening?

Or perhaps the shell weight of 20kg vs 13kg of my e5's have discouraged progress?

[phil_kirk]

Humm!  i didn't want to say that 20KG sounds a bit heavy for just the hull shell.

Andy,

I suspect the shells that you made for us were lighter than 13 and 8kg respectively.  As I mentioned above when bonded together with bulheads (1.9kg) and the aft beams (1.5kg) and centreboard case (probably another 0.7Kg ) it still came to 23Kg. That's not mentioning the bog fillets to bond the bulkheads in and deck on and connecting laminations for some parts.  You did a great job as i expected.

[Banshee Ambulance]

I think, as with any measurement it depends on how it is done! In theory of course, this should not matter for the case of measuring weight, but a boat is not an easy thing to measure on the bathroom scales. 20kg might be the figure that is thought to be correct but in my view, each technique for measurement will have its own assumptions and innacuracies. That is unless you have a pair of Cherub sized scales! Perhaps sharing measurement techniques would gain more than 'yours is heavier than mine'!  

[phil_kirk]

Good point,

My method was based on a set of bathroom digital scales.

the boat was sat on two battens of wood 1 at the bow and one at the stern.

In turn the scales were placed under each batten and that end of the boat was weighed.

The scales were zeroed after the batten was sat on the scales.

We had previously checked the scales by placing 1 Sarah on them. 

A Sarah is a british unit of weight measurment.

[simon_jones]

I see you very wisely didn't mention what one Sarah is equal to. As it might have been one black eye

[doug1720]

Hi,
I am back on the project.  I have spent only a few days in Dubai this year and so impossible to get aything done....work commitments

Just finished the dagger board and daggerboard case and will plan to put the crew deck in when I return from a break in the UK....just bought a house in Lymington...walking distance from the yacht club!

Thanks for all of the comments.

My son who is at University in UK is thinking of getting a Cherub!  So perhaps I will be on the water quicker than I thought!

Doug