New project

[Malcolm FraryParticipant @malcolmfrary95515]

As described, if I read it correctly, there is still an unsupported join in the middle of the mast/fin system. This system acts as a lever. Such a join is a weak spot in the length of that lever. If you use a crowbar, you don't saw part way through it. The alternative, to transmit the forces through the hull and rigging, is a much heavier hull construction, putting weight where it isn't wanted.

While the weight of the brass insert might provide some ballast, it won't be where it is needed on a model. What works on the real thing at full size restricts where and when a model can be used. Because the wind that the model experiences is multipled by the square root of the scale (e.g. 1:12 scale boat, nice 10-12mph breeze is a near 40mph gale for the model), it needs all the righting moment it can get. Raising the center of gravity will not help. Everything ablove the ballast weight at the bottom of the fin needs to be light, but strong enough to survive the forces involved.

[Chris FellowsParticipant @chrisfellows72943]

Thanks Malcolm – where do you think the unsupported join will be?

The section of brass keel will only provide a little of the ballast/righting moment, it will still have a bulb keel attached.

I'm going to see this through, if it doesn't work so be it, I can always have it as a static model and build another one!

I'm doing the conventional builds with my other Faireys so this is about doing something different for me and the challenges that it brings, it's all part of the fun.

I'll post up some drawings once I've done some more work on them but the design will probably evolve after that. If I need to add some more "construction" to close the loop of forces within the mast/fin system then I will do. I'm still thinking though that due to the relatively small sail area that my over engineering will cope.

[Malcolm FraryParticipant @malcolmfrary95515]

"The mast will be located on the top of the brass keel and also restrained where it passes through the cabin roof. "

What is going to transmit the force from the fin to the mast? As described by both Ray and myself earlier, ideally the fin and/or its fixing passes through the hull bottom and goes to a fixing at or near the deck. The mast going down, through the deck to the hull bottom forms the required overlap. No flexing force on any part of the hull.

A deck stepped mast requires rigging strong enough to hold the mast up against the wind forces, and a strong enough hull to transmit these forces to the fin without buckling the hull (been there, got the T shirt). Looking the other way, a fin that effectively stops at the hull bottom needs the rigging, but can't have it because it is under water. The fin itself can terminate at the hull skin, but does need a strong rigid member to pass upward to the deck to benefit from the support that the deck beams will give (or even just the deck itself).

The force of the wind on the sails is opposed by the weight on the other end of the lever. While it is finding its equilirium, the surface area of the fin acts as a damper. A sudden gust can put a surpising amount of force on it, and whatever it is fixed to.

[Chris FellowsParticipant @chrisfellows72943]

OK, thanks Malcolm I understand what you're saying. I was thinking that the brass being 8mm thick would be man enough to deal with the forces between the mast and keel. Maybe it will be but I can see that unwanted forces i.e. twisting might be applied to the hull. It's going to be heavy and strong being plank on frame but it will be easy enough to introduce a "deck" below the top of the hull (the superstructure will be removeable so of limited strength) to equalise the forces.

I shall crack on with the drawings!

[Ray Wood 3Participant @raywood3]

Hi Chris,

The proof of the pudding will be in the building, as you have plenty on the go, I'm guessing we may have a while to wait before finding out

Regards Ray

[Chris FellowsParticipant @chrisfellows72943]

You're right there Ray, I said it was going to be a longer term project!

But with not being able to do much else now, especially outside, I'm back in building mode and doing some at evenings and weekends.

And today I received quite a large delivery from SLEC which included some of the timber for the Fisherman! So I'm keen to get started!

[Ray Wood 3Participant @raywood3]

Hey,

Christmas came early with a SLEC delivery nothing better! Happy building

Regards Ray

[Chris FellowsParticipant @chrisfellows72943]

Posted by Ray Wood 2 on 21/11/2018 22:20:20:

Hey,

Christmas came early with a SLEC delivery nothing better! Happy building

Regards Ray

Partly that and partly from a birthday earlier in the month. Was going to stock up at the Model Show but couldn't go until the Sunday and most of what I wanted they hadn't got.

But I still need a couple more motors, props and prop shafts so more Christmas pressies!

Plus I've been thinking about an essential pillar drill! How I've managed all my life without one I'll never know!

Cheers, Chris

[Dave MilbournParticipant @davemilbourn48782]

Chris

For what it's worth, I bought a pillar drill from Machine Mart about ten years ago. **LINK** It's been fine for all my modelling and DIY needs, although I would want something a little more precise in an engineering workshop. Either way you will wonder how on earth you ever did without one!

Dave M

[Chris FellowsParticipant @chrisfellows72943]

Dave – been doing a bit of Googling and looking at reviews and one from Machine Mart is on my radar, which is where I bought my Record scroll saw from.

Trouble is I keep looking at other essential tools and equipment as well!

Chris

[Chris FellowsParticipant @chrisfellows72943]

Bumping this so I can find it easier for reference!

[Author]

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