Please Comment on this design

[wimal]

Dear All

Few months ago, I commented on boat building in Sri Lanka and said that I would start building a new FRP boat. I have completed new mould out of a plug made from my own design and first boat is already launched. Multi-day fishing boat of 31 tonnes (full load displacement).

Dimensions
LOA = 42'
B= 13'
D= 6.5'
Draft = 4'-2"

It does around 12 knots at lightship condition of about 10.5 tonnes with 72Hp second hand engine which is quite satisfactory to the other boats built in Sri lanka. Shape has been optimised to give better stability and minimum resistance with satisfactoy stowage capacity. The vessel has got hard chine lines that has reformed to bilge keel at the after ends
Please give any comments. Is it possible for me to get the patency for the design?

[Guillermo]

She seems to be a nice fishing boat, with somewhat more freeboard than the the one we are used to in Galicia. Speed seems to be good, well over hull speed, so indicating an efficient semi planning hull. Anyhow I would not spend my money in getting a patent for that.

[longliner45]

looks like a good snapper boat, I like it.whats the payload, yea 3 deck reels on each side and 2 astearn,,,,,when we leaving?

[Wellydeckhand]

Positively good shape........ fast hull but as longliner45 say what load she can hump? U are installing a trawl? or what? Its size is common and would be copied by Sri Langkan so patent is wasting the doe....... i am with gilly

[Gilbert]

I like it too. Sell plans and/or sell hulls or boats from the mold. I doubt that a design patent is worth the trouble, at least I know I wouldn't bother with it.
It looks very good.

[Guillermo]

For safety reasons I would ckeck if the freeing ports area is at least equal to an area in sqm equivalent to the 7% of the length of deck well, diminished in proportion to the difference between 90 cm and the actual height of bulwarks. I'd increase somewhat the height of guardrails (90 cm, if possible ), at least at the sides of the wheelhouse and in the bows, keeping them low only where strictly needed for fishing labours.
What about her stability? Do you have any displayable GZ curves for the several cargo conditions?

"....The vessel has got hard chine lines that has reformed to bilge keel at the after ends...."
Could you explain this a little bit further, or post an sketch?

[wimal]

Thanks everybody for all comments that made me please.
I have conducted the inclinining test and the vessel has lightship GM of 0.7m and the stability at other loading conditions are also satisfactory. I will post GZ curves at several loading conditions. Already 5 boats are in the process of building.

Why I was keen on patency because Srilankan boat builders may take a mould out the sold boat and may start manufacturing at another place.

At the forward end step of the hull start as a chine line and beyond the midship shape has been gradually droped to form the shape of a bilge keel.

[safewalrus]

Looks a useful vessel for local weather conditions in your part of the world, somewhat surprised at the amount of freeboard for a fishing boat tho' Still as I said it suits your local conditions not mine! Like it!

Wouldn't worry to much about other Sri Lankan builders as long as you keep the price right! If you charge too much you only have yourself to blame and deserve to get the boat copied (which of course will happen!). I think the main problem of copies would be further afield, where you wouldn't know they'd been copied anyway!

[Guillermo]

Originally Posted by wimal

...I have conducted the inclinining test and the vessel has lightship GM of 0.7m and the stability at other loading conditions are also satisfactory. I will post GZ curves at several loading conditions...

0.7m GM in lighship condition doesn't seem too much to me (Nickum recommended 0,61m in loaded condition for small fishing boats and our rules in Spain are going to ask now for 0.7 as a minimum in the worst condition), but to give a better opinion I'll wait till you post the GZ cuirves.

Originally Posted by wimal

...At the forward end step of the hull start as a chine line and beyond the midship shape has been gradually droped to form the shape of a bilge keel....

Are this bilge keels needed to beach the boat or to dampen rolling?

[wimal]

Dear Guillermo


Please find the GZ curve for the fully loaded condition. GM recommended by FAO guidlines is 0.3 m.


Wimal

[Guillermo]

Sorry, wimal, I had forgotten about this thread.
Static stability in that load condition seems to be good enough under the IMO code on intact stability (vessels over 24 m). As FAO recommends for small fishing vessels to comply for all load conditions the same criteria as the big ones, your boat having a lightship initial GM of 0,7m seems to be OK for other load conditions.
I suppose openings such as hatches, etc, are watertight, so the curve of stability is valid trough all heel angles showed.
Additional important recommendations are the following:
- The heel angle for hatches that are kept opened when fishing, shall be at least 20º
- The GZ curve should be positive up to 80º
But you most probably probably already know this.
Cheers.

[Leonard]

Dear Wimal
I sailed for 5 years of my life for a living and I have now just obtained an agency to supply all the raw materials needed to build Fibreglass boats, from the CSM, Adhesive, Resins, Gel Coats Etc.

The difference I belive between the products I am supplying and others is that my principals are willing to help customers who purchase their products with, Production Techniques like Hand lamination, Vacuum bagging, Resin infusion etc and also they will help you with designs, redesigning an existing Hull by improving design parameters such as weight, speed, structural designing etc.

Please feel Free to contact me if you require to talk further about this

Rgds
Lenny

[wimal]

Mr. Leonard

Please email me the detail of the material, product name, country of orgin etc.

Wimal

email: wimal@mech.mrt.ac.lk