Steel plate Thickness

[SailDesign]

As gonzo says, if they don't ask the question, how are they going to know that they are heading up the wrong path. I would rather they ask the question, get the answer that they are in over their heads, and then they can either take the advice given, or go on their merry way wondering why the boat don't float right.
Steve

I agree with the attitude of the other guest.

If the original poster could read Gerr's book, he would not be here asking his question. He would be reading the book.

If he had the ability to compare Gerr's scantlings to his needs, he would not be here.

Perhaps the best advice would be for him to hire a professional to spec the boat and then to supervise the construction.

If he had the ability to see that as a reasonable path, he would not be here.

in any case, I expect the original poster will go off and make his own mistakes and perhaps we will noever hear from him again.

I built my own fishing trawler. It is 100'(l) x 32'(w) x 17'(h). I used 3"x3"x3/8" angle at 12" intervals (similar to framing a house), 3/16" sheet metal for the skin, a 6" steel reinforced concrete slab in the bottom ( for balast and integrity). It has 15 bulkheads. It's powered by a 351 cleaveland with a 36" prop set to 45 degrees. At idle speed, she pushes 5 knots. at top speed, she's at roughly 25. Measure your steel by the amount of displacement you will have. Aside from the occasional "rogue wave", you need only keep out a "typical" amount of water. To account for the abstract conditions, increase the horizontal pressure by 2x. In summation, if you are going to set 3' down in the water, build your steal boat to resist 6 vertical cubic feet of water. Suffice it to say, if you use the skeletal and skin pattern that I have used, you could set your boat nearly 100' down in the water. As a mechanical engineer with post graduate hours in fluid dynamics, I thought it would be safest to build a boat that could survive a wave that would stand it completely vertical. In that scenario, she would most definitely go all the way under for a moment. That's 100' down! But the concrete ballast would set it "upright", the 15 sealed bulk heads would bring me to the top, and I could "live". Got it? Be safe, and if you don't know, ask! Because you did ask, I answered.

I wouldn't care to take Bruce Robert's word for design details nor scantlings--several of his designs have sunk due to loss of the skeg under normal sailing conditions. He had this wierd theory that loosing a skeg would be a good thing as it would prevent more major damage when under extreme stress.

Well, in general, the scantlings mentioned are probably typical for a displacement craft assuming longtitudinals 18" on center, and frames at about 44" on center, per Gerr.

[Dutch Peter]

If you feel confident to design your boat according to a book, go ahead. Some fine boats have been build like that, but remember, we seldom here of all the projects that failed ven before they touched the water.
If you want some more security (construction wise), buy the Rules from one of the Class Societies or their calculation program. It's more expensive than a book, but less than having it checked by a proffesional designer (5700 US dollars?).
If Lowcountrydata is willing to share his secrets of his design with the forum, one of the profs might want to take a good look at it.

"to never shoot, is to always miss" (rough translation of Dutch saying)

Good luck,

Peter

[water addict]

Consult an engineer if you can afford it. 65' is a big boat. A good set of sails will likely cost you $60000 or so. $5700 is nothing in the scheme of a 65' boat. Seriously, if you are debating $5700 for the most important component in the safety of the boat, ie. the structure, don't "wing it". Don't try to follow some off the shelf text or reference if you are not an engineer. You will miss some assumptions and make a mistake - guaranteed. And something will break, and someone will get hurt.

" The sea is selective - slow in recognition of effort and aptitude, and fast at sinking the unfit."

[MikeJohns]

I'm with guest

If you know so little as to not even know the basics (ie scantling rules) then what are you doing designing a 65' yacht ? Surely you go take some classes and read some books before crying for help on a forum for design specifics.

Too many people seem to think that yacht design is a trivial pursuit and that the engineers/designers fees are excessive. Try getting an engineer to design you a custom car chassis or anything else with dynamic loads and see what you pay.

Some yacht designers are not Engineers or Naval architects and simply design to scantling rules basically copying and modifying. Some have good results, with others their skegs fall off !

Hi all, im new to this forum and this is my firts post so please be gentle

I feel im with lowcountry here.. ok, his numbers may be guestimates but they are pretty close, just slightly abow bruce roberts specs for his roberts 532.

Lowcountrys specs may still be guestimates and if so they outta be shecked by someone whos not guessing. But, what if he _has_ been looking in the books 'n' rules and he has done his homework. ive seen his question elseware and he got his head pounded on there too.

Lets say i read all the books in the world about scantlings and rules and whatever and construct my own boat 'cos i want my own creation but i still feel id like a second oppinion, so i go to some forums to ask a pretty simple question like
-"ive got some numbers here, do they look about right or not?" and the answers i get is -"i wont aswer 'cos u gotta read and figure it out your self!"

Im sure my MD also asks for secund oppinion occasionaly, that doesnt mean that ill tell him that he cant suture my fingre or sometyhing else more lifethreattening without looking in a bunch of books first.

I dont know lowcountry and i have no clue about his intentions or plans but i havt seen or read anything that says that he wont go to a qualified person to check his design after he has gotten a second oppinion from here and elseware. If I were to do a design of my own id put some pride to do my homework and get the scantlings right by my self 'cos thats a part of the construction and only getting a qualified person confirme my work. If i didnt do it on my own i could very well have had someone desidning something for me, all i had to do was to payup.. or i could even go to a marina and by a bout thats alreaddy in the water, that would be convinient and easy all i had to do was pay and be a proud owner of a boat. But i sertainly would be even prouder if i was the owner of a boat that iwe constucted, built, put in the water all by the book paid with less money but with more blood 'n' sweat... if i only could get some help on the way and not pounded on by the common ppl saying that "go to a NA!" you cant do that.. I tell you, ive got that to.. iv got it from my marina when i told that i wanna build a 53feet sailer outta a pile of steel, or even from my parents when i bought a pile of glass and glued my fishtank or when i told that i was going to change engine in my current 32feeter (steel trawler like) all on my own. its pretty frustrating when asking a simple question and not getting a simple aswer..

I feel that anything is possible cos it has been done before by others so why not again by me or lowcountry in this case, all hes asking for is a straight answer, then what hes doing with it is up to him.

so.. ok im done now give it to me

-- Per Larsson / Sweden

Strangely folks I'm looking at this size steel trawler too. I have had contact with BR various times and believe he is very competent indeed. The price quoted above probably includes the FULL SET OF CUTTING files... 5200$ is a bargain dude !!


lotsa luck

George

[Wynand N]

DUDLEY DIX YACHT DESIGN

Dix 65

Radius chine metal cruiser

LIST OF MATERIALS FOR HULL & DECK

The following list of materials is approximate and intended only for calculation of approximate costs. It is not intended to be used for the ordering of exact quantities of materials for construction.

Lengths and areas are based on the actual amounts remaining in the vessel without any allowance for building stocks, temporary framing, bracing etc nor for wastage in cutting to size and shape as required. Such wastage is dependent on the skill of the builder.

MATERIALS FOR STEEL CONSTRUCTION

3mm [1/8"] Plate - 120sq.m [1292sq.ft]
4mm [5/32"] Plate - 100sq.m [1077sq.ft]
4mm [5/32"] Plate rolled to radius - 50sq.m [539sq.ft]
6mm [1/4"] Plate - 5sq.m [54sq.ft]
8mm [5/16"] Plate - 11sq.m [119sq.ft]
10mm [3/8"] Plate - 19sq.m [205sq.ft]
20mm [3/4"] Plate - 0,1sq.m [1sq.ft]
6x50mm [1/4x2"] Flat bar - 18m [60']
6x100mm [1/4x4"] Flat bar - 8m [27']
8x35mm [5/16x1 1/2"] Flat bar - 126m [414']
8x50mm [5/16x2"] Flat bar - 459m [1506']
8x60mm [5/16x2 1/2"] Flat bar - 94m [309']
8x80mm [5/16x3 1/4"] Flat bar - 100m [328']
10x100mm [3/8x4"] Flat bar - 17m [56']
38mm [1 1/2"] OD tube with 3mm [1/8"] wall - 2m [7m]
76mm [3"] OD tube with 5mm [3/16"] wall - 5m [17']
101,6mm [4"] OD tube with 6mm [1/4"] wall - 33m [109']
152,4mm [6"] OD tube with 6mm [1/4"] wall - 0,3m [1']
4" schedule 160 pipe - 2m [7']
316 S/S 16mm [5/8"] plate 65mm [2 9/16"] wide - 3,4m [12']
316 S/S 16mm [5/8"] plate 195mm [7 5/8"] wide - 2,4m [8']
316 S/S 20mm [3/4"] plate 100mm [4"] wide - 0,7m [3']
MATERIALS FOR ALUMINUM CONSTRUCTION

Plate is to be of alloy 5086 and extrusions are to be of alloy 5083 or their respective equivalents.
4mm [5/32"] Plate - 120sq.m [1292sq.ft]
6mm [1/4"] Plate - 100sq.m [1077sq.ft]
6mm [1/4"] Plate rolled to radius - 50sq.m [539sq.ft]
9,5mm [3/8"] Plate - 5sq.m [54sq.ft]
12,5mm [1/2"] Plate - 30sq.m [323sq.ft]
20mm [3/4"] Plate - 0,1sq.m [1sq.ft]
8x50mm [5/16x2"] Flat bar - 18m [59']
8x100mm [5/16x4"] Flat bar - 8m [27']
38,1x38,1x3,18mm 1 1/2x1 1/2x1/8"] Angle - 126m [414']
50,8x50,8x3,18mm [2x2x1/8"] Angle - 459m [1506']
12x60mm [1/2x2 1/2"] Flat bar - 188m [617']
12x100mm [1/2x4"] Flat bar - 117m [384']
38,1mm [1 1/2"] OD tube with 6,36mm [1/4"] wall - 2m [7']
76,2mm [3"] OD tube with 6,36mm [1/4"] wall - 4m [14']
76,2mm [3"] OD tube with 12,7mm [1/2"] wall - 2m [7']
101,6mm [4"] OD tube with 6,36mm [1/4"] wall - 33m [109']
152,4mm [6"] OD tube with 6,36mm [1/4"] wall - 0,3m [1']
115mm [4 1/2"] diam Round bar - 2,5m [9']
25mm [1"] plate 65mm [2 9/16"] wide - 3,4m [12']
25mm [1"] plate 195mm [7 5/8"] wide - 2,4m [8']
30mm [1 1/4"] plate 100mm [4"] wide - 0,7m [3']

http://www.dixdesign.com/dix65mat.htm

Incidently, I built this yacht on the web page

Wynand N

[SailDesign]

Originally Posted by Wynand N

Incidently, I built this yacht on the web page

That's a pretty small building shed, Wynand.

[Wynand N]

Hi SailDesign,

You quite right, that is a small building shed. Basically used to store my compressor and shotblasting equipment.

In my factory workshops out of shot there were at the time a Dix 38, 2 x 34ft v/d Stadt and Dix 57 in it under construction. The Dix 65 was just to high and wide to go through the doors.
I apologise for not being like the yanks, bigger, larger, louder ...and the damn imperial system......

But seriously SailDesign, it is a nice boat with beautiful modern lines, especially for a steel design.

Go well

Wynand Nortje

[B. Hamm]

Asking for a professional's advice generally isn't free, your doctor I'll bet won't do it for free either, why should a professional boat designer?

Bill H.

[D'ARTOIS]

Originally Posted by LowcountryData

Hello all,

We are currently designing a 65' vessel and are having a hard time getting the recommended thicknesses needed before we can submit out plans to a Marine Surveyor.

We have asked the major builders ... particularly Bruce Roberts, but without a purchase of their plans we have been basically turned away.

We need thicknesses for the following areas and any others you might think of;

Areas & Currently suggested thicknesses are;
keel = 3/8"
bottom hull = 1/4"
side hull = 3/16"
ribs = 1/4"
topside deck = 3/16"
stringers = 1/4"

I see many posts in here referring to "mm" does anyone have a conversion table handy???<LOL>

These we have aquired from several sources, the surveyor will not do any recommendations due to insurace reasons, so we respect that. But he did recommend this site so here we are.

Our vessel most closely resembles a NY65 or a Voyager 65, that was why we wanted to get Bruce Roberts input but alas 5700$ to get the answers we want didn't seem reasonable at all.

Any help or advice would be greatly appreciated,

Thanks in advance,

You may go ahead with those figures, based on st 42 to be bettered by using grade A