Krick Gulnara Build

[RobertV]

I plan on doing a Gulnara build in the next couple of weeks. Does anyone know of a previous build thread somewhere online ? On top of that, I am toying with the idea of powering this ship. I thought of maybe using a Graupner paddle kit and using one or two unfurled sails for looks.
Will a keel be necessary and how can i figure the dimensions necessary if so.

Any and all ideas and thoughts will be greatly apppreciated as I am extremely good at missing the obvious as shown by my M-15 build. Thanks


Robert :D

[Umi_Ryuzuki]

I don't recall anyone building any "Krick" kits on the boards, your's would
be the first. :) Pat Tritle did a Santa Maria sailing ship, but I don't recall
how he ballasted the model.

If you have even just a couple sails unfurled for show, if they catch the
wind, it will cause the model to heel over. I would plan a mount for a
detachable keel. That would allow you to play with the length, weight, and
balance of the model. A rule of thumb for me has been, to double the depth
of the keel when translating a sail boat plan to model sailboat.

I look forward to seeing the build up.

:)

[patmat2350]

info: Gulnara, 1050mm in 1:50



http://www.jotika-ltd.com/KitPics/LRG/GULNARA_lrg.jpg

[RobertV]

Umi- doubling the keel height, is the height for keel measurement ... waterline to keel or top of bulwark to keel.

Robert

[patmat2350]

Robert, it's a truly sliding scale, depending on how big your model is... so 2x is just a starter.
Here's the deal: For righting, the keel is not so important as a dynamic damper (like trying to sweep a broom through water), but as a lever arm with a weight down low... as the wind tries to knock the boat over, the weight wants to right it.
Start with a 1:1 sailing boat that has a good match between keel depth & weight and sail area. Shrink the boat to a (large) model, say 1/3 scale. The sail AREA is now 1/9 of the original (width x height), while mass/volume of the hull (and keel) are >> 1/27th << of the original, yikes! So the righting ability is now decreased by 3 times more than the sail's knock-over ability... in other words, the model sail will overpower the model keel. Now think about a 1:50 scale boat!

So how deep should the "false" keel be? Depends on how much you shrank the model, and how hard a blow you want to remain upright in (oh no, scale wind too??), and how much sail you hang on the model.

But without a doubt, deeper is more stable... and don't forget that weight in a keel bulb is what makes the difference.

[RobertV]

WOW !! The entire beige colored piece is the lead weight? would a deeper positioned weight, maybe with wings cast on , be helpful?
Just curious - how did the real ships stay upright. Wouldn't the entire hull have to be filled with ballast?

[patmat2350]

No, there's a lead bar UNDER the plywood piece, look closely. And the plywood is rigidly attached to the hull with draw-screws. Also note the rudder extension.

Yes, the real boats would carry stones (or later, maybe scrap iron??) in the hull... but no deep keel, simply due to the scale effects (in 1:1, lots of righting moment even with the ballast "within" the hull).

And since your Gulnara has no deep keel to begin with, you'd be looking at something similar, if not so big, since you won't be carrying much sail.

I just spoke to a fellow who built an Eppleton Hall model (UK sidewheel tug). Even with no sails, he felt that a false keel was needed for stability, due to the narrow hull and the effects of the wheels wanting to roll the hull.

[RobertV]

See it ! Thanks for the info. I will have to ponder on this awhile.

[RobertV]

Been working on the kit -I ran into a problem shaping and planking the transom. Not much info on the shape or angle before fitting of the cast side window housings and the precut decorative transom piece. Any ideas?

[patmat2350]

pictures?

[RobertV]

Will post pics when I find my camera - my eight year old fancies herself an artist.