Hull Shape

The proportions are more typical of a vessel for shallow protected waters than one where seaworthiness is important. Also, asking for a generic CAD file shows a lack of understanding of design and vessel behavior. Perhaps the OP can indicate what his intended goal is.

 

Many projects are initiated from the shapes of an existing ship and modified until the new vessel forms. This can be done starting from a drawing on paper, a table of offsets, or using a CAD file. I do not understand why request a generic CAD file is "a lack of understanding of design and vessel behavior". Maybe you should explain in more detail your reasons for this statement.
Most CAD programs include in their databases various hulls types, as templates, which also makes me think that the request of Northwindii is an entirely normal practice.
Of course, all this may seem strange to anyone who is not boat designer but, in my opinion, the way things are.

 

The particulars/ratios given very closely match any number of expedition yachts.
Off the top of my head I can think of some designs for ferries running between islands in the pacific that match them well also.

I'll say it again: the tiny amount of information given isn't enough to accurately declare that the planned design is "good" or "bad", nor any other adjective. An SOR and more data on the vessel is required for that.

 

Gonzo, and to a lesser extent Rastapop, is right on here. The dimensions given are effectively for a shallow protected water car ferry. They could also be applicable to a restricted seaway vessels, such as "expedition" yachts which never voyage in heavy seas or a vessel restricted to the Pacific trades. A vessel of this size would kill people in a "all weather" sea route in the North Atlantic.

At issue here is the length to draft. 135 ft is almost an exact match for a 5 second period wave and a half wavelength for 7 second period. And this is important because for most sea spectra between SS 3 (Hs min 3.6') and 5 (Hs max 10.6'), 5 seconds is the dominate period; either being the period of maximum energy in SS3 to being the average period at SS 5 with 7 seconds being approximately the period of maximum energy. These two factors will drive the pitch and heave, so the selection of this length needs a depth, bow and stern, to prevent forefoot or propeller emergence Given that 8 ft is the draft which is barely half the minimum and less than the max, slamming is almost assured, with the possibility of foredeck submergence unless the bow is very high.

Added to the unfortunate selection of length is the beam and the desire for economy as Northwindii stated in his first post. As Ted Turner once remarked "even a t*rd is pointed at both ends". This means that to get to the maximum beam the shape has two options: force buoyancy into the ends giving a high block, or fine the ends to get the desired "economy" . By fining the ends, this pushes waterplane area to midships which exacerbates the poor sea performance by increasing heave and reducing the ability of the bow to lift in the seaway.

FWIW, this is old hat. Once in the Age of Exploration vessels it was rare to find historical vessels of the 135' range with a drought so shallow. Looking at late 17th to 19th century sail frigates about this size, you will see drafts of 12-14' and bluff, lifting bows. By the late 18th century sailing vessels still had L/B ratios of 4 but had grown to 150-170' LWL. By the mid 19th century ships were approaching 200' LWL and L/B of 5 which allowed fining of the ends for speed but drafts were still much greater that the proportions proposed by Northwindii. From these late sail vessels came the proportions that passed over into early standard series which most hull forms are drawn from.

Rastapop, there are several texts I could suggest that will improve you knowledge about selection of principal dimensions based on expected service, but the fact is Northwindii's original post had more than enough information in it to draw a conclusion about the dimensional suitability to meet the requested goals of seaworthiness and economy. While the vessels service does dictate some requirements (such as Mr efficiencies shallow draft CRUISE liner), given an open spec beam would be less and draft deeper for a well performing hull.

 

Rubbish.

You have no idea where it will operate, or what it will be doing.

You don't even know whether the beam quoted is the waterline beam, nor what the displacement is.

In short, you (and the rest of us) are extremely uninformed about this design, and as such are completely unable to make accurate judgements on it.

 

I don't believe a boat with a L/B ratio of 4.6 could be called a fat boat, Steve Dashew's more contemporary power boats have 4.7 and they don't look all that fat to me (lwl 25.84m. Beam 5.4 6m. Draft 1.53m). Most trawler type boats have L/B in the high 3's. North sea mini supply and fast crew ships around the same length as proposed have L/B 4 to 5 with light ship drafts of 1.8-2.1m (6-7 ft.).

 

Northwindii you can have this older design to sketch on, its close to the dimensions you stated. I can give you a PDF to print in 1:200 scale in metres on A4.

 

Nwindii is a just a solo poster- and is the second thread he has done it in.
Probably not worth investing any time until he actually participates. Getting more and more 'wind up' op's.

 

It seems so.