Overturn in Rough Seas

[Haji K]

Hello,

In the middle of constructing - Semidisplacement 42' Fishing Trawler.

CHARACTERISTICS
Length overall 42'-0"
Length waterline 38'-4"
Beam 15'-3"
Hull draft (@ DWL) 4'-6"
Hull depth 9'-9"
Displacement (@ DWL) 25,600 lbs.
Displacement (@ LWL) 38,200 lbs

Completion status up to date is 70%. In order to suit the requirements of Malaysian Commercial Fishing License,which need minimum 40 GRT, the height of the Main Deck is jack up to 18" more from the Original Design.

On the Main Deck will be locating 3 Metric Tons Fishing Equipments (Longlining Hauler, Capstan & Winch, etc).Now, I'm worry the boat is easier to overturn in Rough seas / Storm than the boat with smaller B/D ratio (Breadth/ Depth).

Thinking to placed the Solid Ballast in the bottom of the Hull to increase the Stability. Please advise the suitable location to placed the Solid Ballast ,since speed is secondary to safety. Regard on the Solid Ballast, please advise the suitable material or combination of materials.

Thank you inadvance for anticipation, thanks

[Willallison]

I would think that you need to employ the services of a qualified naval architect here - ideally the same one who designed the boat in the first place. A detailed weight / stability study is likely to be necessary - especially as this is a commercial vessel that I assume must conform to local &/or international regulations

[Cian Groves]

If you have a lines plan(calculate hydro's from) or hydrostatics data of the vessel you could do an inclining experiment of the vessel to find it's current weight, lcg, vcg etc. Then preform stability calculations with the added weight of the fishing equipment to deem if it's stable.

[Haji K]

Hi Will,

Thanks for your reply.
As a matter of fact, they ( Malaysian Fisheries Dept.) has made a guide line the Boat must achive 40 GRT to award the Commercial Licence. Using their guide line & calculation formula - getting 34 GRT, meant below 6 GRT the target. If I have to go to Jack Up the Main Deck to 18" Higher from the Original Design inorder to get 6 more GRT, any possibility the Solid Ballast is workable ?

Thanks

[Haji K]

Hi Cian,

Thank you very much for your input.
Trying to grasp the Lateral Balance of the Boat from Yanmar Installation Manual - hard to go ( no formal Marine Architect Background). Hopefully and kindly you can direct me to any website to experiment the stability.

Thanks,

[Cian Groves]

Hi Haji,
Some regulations give you a step by step procedure on how to conduct an inclining experiment and then how to use this data to determine if the vessel is safe. I did a quick search and found the following link which maybe of help:

http://www.tc.gc.ca/marinesafety/TP/...rt1.htm#STAB-2

As your vessel is for commercial use I would expect a stability report (including an inclining experiment) would need to be produced for your Marine Department.

Cheers,
Cian

[Haji K]

Dear Cian,

I will go to the website address.
Thank you very much once again Cian for your great efforts & help.
Will contect soon for the outcome, thanks

[Haji K]

Originally Posted by Willallison

I would think that you need to employ the services of a qualified naval architect here - ideally the same one who designed the boat in the first place. A detailed weight / stability study is likely to be necessary - especially as this is a commercial vessel that I assume must conform to local &/or international regulations

Hi Will and others,

Surfing from the Software archive, found out sometime in Feb 2003 you did mentioned "Rhino 2" design software.Since you are having Rhino & Multisurf design software long long time ago, I think your knowledge is very "solid"
regards on Boat Design. By utilizing your software and solid know-how , do you want to help me Sir - by calculate of the hydrodynamic coefficients - much much batter coming with boat motions in regular and irregular seaways (South China Sea) study ?

Download Prolines 7 Demo yesterday, alas !! new driver with Brand New Car - lost control !! Need 364 more days to gain the control . I will forward the existing dimensions of the boat to you. This is my e-mail address : hajikamalharun@msn.com . BTW, I'm still not installing the main deck yet .

Thank you very much inadvance for your great help, thank you