Big ships with simplified hull shapes

Discussion in 'Boat Design' started by 1J1, Dec 15, 2016.

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1J1Senior Member

Hello!
Recently I was viewing the HOSMAX 300 platform supply vessel series & what caught my attention was a very cheap & simplistic hull shape -

- basically the underwater part somewhat resembles a hydroplane's hull. You can get a better insight looking at the GA plan http://hornbeckoffshore.com/public/...drawings/HOS_Red_Dawn_General_Arrangement.pdf & especially a middle section - flat & angular. From specs sheet, Max Speed: 12.0 kts & Cruise Speed: 10.0 kts.
I'd like to know how having such hull shape affects the performance... no maths, just suggestions & thoughts. Would a similar hull (less blunt on plan view though) be capable of reaching higher speeds like 15-18 kn or it would require more power than for a streamlined smoothed hull of same size to reach same speeds?

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TANSLSenior Member

Okay, let's forget mathematics and use common sense to answer this difficult question: Is a hull in the form of a shoe cage more efficient, from the hydrodynamic point of view (I'm not talking about cargo hold volume or stability), than a hull with normal shapes?.

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rwatsonSenior Member

Yes, of course speed would be improved with a rounded bilge, but it doesnt seem a prioroty on the SOR..
Check out the Tank Capacities, Water Ballast, Mud and Methonal - it seems stability and space are the priorities.

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Devu De GoaJunior Member

Construction will be much simpler and hassle free. For such ships which have most of the accommodation and machinery at forward, this is a valuable gain in space. Try comparing the shape for example with this other GA I found on internet.

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1J1Senior Member

Thanks, a lack of rounded bilges on a ship of such size is what confused me at first. As I see, such flat shapes are very common for most of modern built US-suppliers... Vessel in Devu De Goa's post in most of it's lenght looks bulky, with simplified stern & rounded bilges through it's length.
From that pic in my first post, as I understand, most of the water is "heavily" pushed aside by perfectly vertical bow, while less part is "lightly" pushed down & down-aside. I would guess sharp edges where planes intersect create much swirls along the bow in that area as the flow suddenly cuts off on going down & aside... Also, wouldn't angular/flat hull suffer from much stress due to slamming in rough seas?

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