How to build from a design.

How do you build from a design, or do I need someone else to take this further.

 

Now that you have the shape of the boat defined and permission from the designer to proceed, you next:

define the speed that you wish to travel and
- calculate the required horesepower
- calculate the propeller characteristics required

Now that you know the speed at which the hull will travel, you can calculate the forces acting on the hull, such as:
- slamming point loads
- torque loads induced by off-angle wave impacts
- panel loads

With the calculated loads, you can now do some quick engineering calcs to determine:
- structural material type and orientation
- structural core type and thickness
- layup schedule
- stiffening structure form and layout

With all the strength bits worked out, you can then proceed with a general arrangement drawing so that you can:
- calculate weights & centres
- have a measured plan to build from

Oops! Wait a minute! If you have weights & centres, you had best go back to the beginning and run through the numbers again to see if the actual calulated weight is the same as you used in all those strength calcs, 'cause if you're wrong the boat might not perform as you expected, or might even break. If weights match, carry on; if not, do all the calcs again and change arrangements, layup schedule, structural arrangement, materials, etc., to suit. This is the harsh reality of the design spiral.

Everything is Kosher now? Proceed to build your boat.

(Sorry for the unwarranted cynicism, but sometimes I get a little crazy when I percieve that some folks believe that designing a boat is pretty much a process of drawing a pretty picture of a boat and then just "winging" it. A minor variation of a proven hull form built with similar materials as the original works and is called "indiginous development", but a radical change or changes to an existing hull, or a completely new hull design, deserves proper design & engineering before one's wallet and personal safety are bet on the construction.)

 

Thanks for the info....However WOW, you totally blew me away with all that. Except from knowing that a cruise speed mid 30 / WOT around 40, I do not have the tech or know how for any of the rest of that stuff.

 

“unwarranted cynicism”, I don’t think so, more like reality.

Guest,
If you are interested and have the time, there are books that can teach you these things, the list is long but you will find many of them mentioned on this forum. You also have a choice of schools that teach these skills. If you just want to build the boat or find out if it’s worth building and not be concerned with the details than there is many professionals that can do the hard work for you. You will have to pay them but the price will be cheap when the alteratives are considered.

Gary

 

winging it

Guest:
A word of caution on "just doing it" I spent just under $6,000.00 on the plug and mold for a 19" sea kayak of my own design. The end result as far better than expected performance wise. but a summer sanding and slinging resin and glass on 2 plugs and 2 molds to end up with one boat was no fun! I did not do my homework on fiberglass work and I payed dearly for it. I have done a lot of fiberglass repair on work boats but only function was reguired not eye candy. figuring a lay-up schedule for the hull you posted is no small task " pages and pages of math and calculations" You would not go wrong to choose a designer to do this for you or buy stock plans. Gary has a good point too that the info is out there to teach you the ropes if you have the time and the drive. Plus its a lot of fun once you know a little
8Knots

 

Guest,

mmd, 8knots, and duluthboats are on the button..... If you have the passion I might suggest you start with this book to understand all the numbers that you have posted, the others may have some suggestions....

Principles of Yacht Design (I have the second edition)
Lars Larsson and Rolf E. Eliasson

This book will give you a real good start on boat design and understanding of what may be needed to build a boat.

Good Luck

 

Tunnel hulls are particularly difficult to calculate. The slamming impact is different from a vee or round bottom hull, and the data is scanty at best. I suggest you study what builders of similar craft are doing.