Cost Of Traditional Wood Build Vs Various Modern Techniques

ah oh well it would have been interesting to do a few comparisons

doing a few of the wheel house elevations tonight and by say Thursday I will be able to draw up the basic internal structural plan accordingly

what I need to figure out is the size of what a white oak stringer would normally be for a vessel of this size on a 20" center over bulkheads spaced at the distances prescribed

then I would have something to compare the truss system to in terms of weight

I suppose I will just figure up the truss system and see if it comes out to the estimated target weight

 

ok so lets get back on track with some further discussion about simplicity in design of a wood build as apposed to a more intricate design but with greater efficiency of weight

oh the one hand we have stringers over bulk heads with double diagonal planking
a typical arraignment would have the deck house walls landing on the deck and live loaded across to the hull
stringers would be simple beams spanning the distance between bulkheads

I was thinking of altering that basic arrangement to incorporate a few modern details
the deck house walls could instead of live loading be supported on the cabinetry below and mimic a simple web truss
this eliminates the live loads placed on the deck and reduces the size of the beams necessary in order to support this structure
it also adds to the weight the roof could bear before failure by carying the load throughout the structure
some of the stringers could be the bottom cord of another truss also doubleing as shelving in certain areas within the cabinetry and also acting as deflection resistance for the deck house walls system and floor system
the cabin floor beams could also be web trusses and lend support to the keel area and the underbody stringers shortening there span creating a more uniform loading
speaking of which I come up with 50lb sq/ft loading for the vessel Im considering
a max stringer span of 14.5' between major bulkheads
by using a system of interconnected 3/8 ply webbing trusses with 1.75x1.75" cords I'm thinking I might be able to lighten the typical sized stringers needed and reduce the maximum span of the stringers to proximately 36"

 

Perhaps it might be prudent to consider the methods of keeping a glass house intact and in place during a sustained green water moment of say 10-30 hours duration. Sometimes a little extra weight and mass in the scantlings comes in handy.

 

post # 155

got it covered mate

 

Boston,

Mate, in normal wooden boatbuilding the bulkheads do just what you are proposing anyhow, ithe weight of the cabin is not just loaded onto the deck beams, the whole lot is tied together, including interior furniture, it is also stress bearing. It is the clever use of the interior fitout that allows such loadings to be distributed in compression that removes the total load from deck half beams etc. try reading some of the traditional boatbuilding books a bit more before you attempt to re invent the wheel, it will save you a lot of bother.

 

well then it sounds like I wasn't to far off the mark then. I was thinking each cabinet partition and each shelf in the storage areas would lend support to the stringers, basically your right I just never finished out anything but a work boat and that about 30+ years ago. not reinventing the wheel just trying to make the best use of my interior just as you suggest.

I know its in my notes somewhere but what would be a good bit of literature on the subject. I finished elements of yaht design and am not waiting Ruel Parkers sharpie book to arrive

 

That's a very good point. I once picked up a small travel trailer free, because a guy had gutted it. He had no idea that the entire interior was structural--including the bathroom partitions, the counter, the dining nook benches, the bed frame, the drawers and shelving, etc. Apparently, when he started he thought all that stuff was the equivalent of free-standing furniture that had been screwed down.

I did some quick-and-dirty reinforcing, that mostly involved screwing flat boards to the interior walls to strengthen them. Then I stuck a full-sized drafting table at one end, a file cabinet and refrigerator along one side, and a desk at the other end with a bunk over it.

I never even tried to get clear title and register the trailer, and I'd have been scared to bounce it down the road anyway. Instead, I just moved it from construction site to construction site on flat-bed trucks, and used it as a job office for years.

 

ya you got me on that one folks
I was not aware that they were doing that and was wondering why not
brilliant eh
oh well at least I had the right idea

 

The use of cabinets and furniture etc. as key structural elements is pretty standard procedure for all kinds of boats that are striving for high strength to weight ratios.

I got the part about your window design, bullet proof glass, storm shutters etc. from way back when. The viability of all that is another topic for another day. That's not what I'm talking about.

I'm talking about keeping the house from being ripped right off the boat under sustained storm conditions. You're going voyaging with a commuter design not initially intended to press on regardless. There are going to be places where you plan to take this thing where stopping when it's rough isn't practical. To say nothing of a jaunt to Hawaii as you mentioned. The inside passage has lots of hidey holes and is quite well protected compared to the outside. But there many spots where for a multitude of reasons not the least being a lack of local knowledge stopping isn't really a choice. The more extreme the weather the fewer options you may have.

The old time seaboats had small houses and lots of meat. They went to great lengths to tie things together and they didn't do it by striving for minimalist framing members.

Parker's book will probably be helpful. I've one of his books and was impressed with the way his system worked for him. He is more comfortable with plastic fittings than I am but that's subjective in many ways.

 

Even on a backyard boat both time and materials are Money!

I wonder when the use of a computer company that can cut ply for the interior , particularly for an "egg crate" style where almost all the furniture is structure .

To use far fewer sheets of material , water jet cut , that would add loads of strength and save time just might pay off.

Certainly the boat would be stronger and lighter , but so would the wallet.

When could this pay off?

FF

 

hmmmm
we seem to be misunderstanding one another
I am suggesting that he side walls of the deck houses be full height specifically so they can have multiple attachment points, this allows for more glued surface area and a far more monolithic structure which is inherently stronger than a system relying on a few larger members.

I am also suggesting that the major components of this wall by webbed together through a top and bottom cord integral to its construction with deviations in the uniformity of the webbing kept to a minimum

these two full height walls would then also have additional support from deflection by creating an integral link between the stringers on the hull sided with it in the form of shelving at which point you now have four major attachment points along the bottom two thirds of each post of the house structure supporting the windows and roof. I cant imagine that a simple single post attached at only the deck carlins is going to be somehow stronger

a simple DF beam spanning 14' on 19.2' centers and supporting 60lb/ft would want to be a 2x10 and weighs between 3.5 and 4 lbs/ft depending

a TJI 9.5 depth 210 series weighs 2.3lb pr foot and can do the same job for about a 1/3 savings in weight

fewer larger members have more stress placed on fewer connections whereas a larger number of lighter members have less stress placed on more connections
combine that with the weight savings and you end up with a stiffer faster stronger structure with more even loading

I'n not talking about skimping on framework Wally Im talking about optimizing the structural characteristics of the layout into a monolithic build
egg crate as some folks call it

Fred I think the pay off would be at the pump every time you filled up
lighter stiffer structures move easier through the water. The one thing that no ones mentioned yet about aiming for light weight is comfort of ride. a really light boat is bound to be less comfortable.

I'll know more as I move through the process and then I can play with it from there
began working on the layout of the forward section last night and am struggling with were to fit the freezer in. someone mentioned that a deep freeze large enough to fit a good size fish into was a must. I was thinking a 4x2x2 would be more than enough but were to put it that has good access is the trick.

cheers to all
B

 

Misunderstanding indeed. "be supported on the cabinetry below and mimic a simple web truss " painted a different picture in my mind then the one you perhaps intended. I'll wait for the drawing.

 

Yesterday it was 50lbs/sq ft, today it's 60lbs/sq ft.....where are these numbers coming from and what do they apply to? Is this a snow load....

If you are speaking about deck loads....the forward 2/3'ds of the boat should be designed for a minimum of 2' of water, that's 128lbs/sq ft....or double your first guess. And 2' of water is nothing in the Gulf of Alaska.....

Design Loads throughout the structure will change with expected sea state, speed, size of vessel, etc......go back and re-read the Scantling Determination Chapter in Principles.

 

LOL,
The teacher can be very strict about not doing your homework when the classroom is the Gulf of Alaska.

 

Lmao
nope not a snow load
but I did appreciate the humor in that last

I took the number of sq ft of submerged hull and divided it into the projected weight of the boat and came up with 63.5lbs pr/ft
it was so that I could compare the two differing styles of joists I have tables for
which are at 60lbs a foot
I figured it was close enough for a comparison of the weight savings in the two different kinds of beams

there is a scantlings book that someone recommended as well
Ill have to search my notes but Im sure its in there somewhere