The image posted is of a jet-powered wingboat design (it extends the logic of the tunnel hull design to the point where the entire craft is lifted out of the water on an induced cushion of air). Also, if someone has links to hydrodynamics, and the role of steps and chines in hull design, I would be greatful. Location: Gulf Coast You intended to take this as plane at the high speed runs. Location: Jamestown, RI, USA Peter T - I'll see your concerns about the nose falling, and raise you a pair of tailerons. From the positioning of the weights (visible) on this thang, I'd say that the nose will be fine, and the dynamics will take care of it.
I haven't found any Tailless design stuff yet, but I know I have some, so I'll have a look over the next few days.
Location: Southern England These two sites are worth a look for extreme boats (and the Bladerunner) some of which are similar to the boat here.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. But the flat-bottom skiffs tend to porpoise and pound, and I might occasionally tow a skier or want to cruise sort of fast, while a 40' deadrise is a bit much for me. So, I have been looking for shoal draft, chop handling, and ability to cruise comfortably on plane.
Then I started drawing and -surprise- same up with a 20ft skiff (is there a prize for the billionth design?).
I realize it might not perform better than other S+G designs (at best) but to me the look is better, with a couple extra panels. Location: maine Regardless of what she'll do motoring, I saw nothing in the lines to prevent sailing rather fast with the right rig. Location: Pontevedra, Spain You'll have to keep that forefoot out of the water when planning, or it may induce directional instability, in my opinion. I have only crude guesses about trim under power at this stage, but with an outboard, it should not be hard to have the bow trim up. Now all I have to do is turn the aft stations to true monohedron and I would have something I could buy on any street corner-the homogenized skiff! Location: Sydney I think your second design looks much better - no need for that pointed forefoot in the first one, and that wedge did look like the drag would outweight the benefits.
Location: Virginia, US The transom is not warped as you can see from the (unfaired) views here. BWD View Public Profile View BWD's Gallery Find all posts by BWD « >small jet boat design help?
Location: Kingston, UK Just to clarify, I'm referring to the process of creating flat templates for the planks from the full scale line drawings. Sorry if these are stupid questions but I'm new to boatbuilding and no-one seems to be able to tell me exactly how the actual build process works.
Location: Oriental, NC Gus, Here is a thread on another forum of a recent lapstrake build of mine.
Once I have finished designing a hull in the software, I use the feature that creates a cutting pattern for each panel. Every time I've designed a boat in my software and used its patterns like this, the results have been practically perfect.
To lap the strakes I would simply cut them an inch or two wider than the patterns illustrate, depending upon how much I want them to overlap. I did not know if you had actually done this to completion of a clinker boat from a computer program before.
If I try lapping the panels I will probably still use pre-cut plywood strakes and epoxy filler instead of bevels at the joints.
Or I can put more time and effort into computer modeling and come up with precise patterns specifically for lapped strake construction.
One of my concepts for the construction of a light weight lapped strake boat is to use thin plywood strakes, perhaps only 4mm or 5mm.


John Welsford designs boats with stringers installed first on bulkheads and frames, then his strakes are 'cut to fit' on top of the stringers, each one beveled to the next, with the stringers visible inside the hull. I would set up the bulkheads and frames on a strongback or on the keel if the boat has one, then alternate the installation of strakes and stringers -- install a strake first, then a stringer, then another strake, then another stringer, etc.
In this type of construction the hull should be as self-fairing as in a strip planked boat. Granted this is only a concept at the moment, but I can see no reason why it won't work, although I'm sure I will discover some issues the first time I try it. If a boat has no need for frames for strength, I see no reason to ever include them in its construction.
Boats like Welsford's use few strakes and tend to show a thick lap at the turn of the bilge caused by the small radius there and thinner laps elsewhere. Location: Southern England Renato Levi Wrote three books on the subject of designing Powerboats.
Best book currently available on powerboat hydrodynamics is Hydrodynamics of High-Speed Marine Vehicles, by Odd M. If you are working in Aluminum, go to ABS, Lloyd's, or ISO and get rules for construction of high-speed vessels. Jet boats are tricky, most major water-jet manufacturers have lots of data on what works, talk to the supplier.
A phenomenon known as porpoising can occur if you are not caqrefull of what you are doing on the bottom, particurly in the 6' infront of the transom. Make the delta pad on the bottom nice and long, no-one says that the boat needs a 'keel', where the bottom sheets meet to form the vee. Look at other jet boat manufacturers and what they do, we spend many hours making sure we get it right so we can sell a safe and well performing product. As has been said the key is power to weight and planing area in both laden and light conditions.
On the lake I grew up on, we had a nieghbour who owned one and we(my buddy and I) plotted hpw to get a ride in it once a year and it was the holy grail of life to get a ride in that! Location: Eustis, FL There's no screw ups in the design of a boat like that, so if you're guessing, you might pay dearly for it. Originally Posted by PAR There's no screw ups in the design of a boat like that, so if you're guessing, you might pay dearly for it.
The reverse chine and lift strakes will help keep the boat from swapping ends in tight turns, help, not keep it entirely from swapping ends. Most people with some experience driving jet boats think they have a handle on skinny water and tight turns, this run through the canyon, opened my eyes. Stay away from any fibreglass, maybe you will save some weight but damage hitting rocks will be hard to fix. Originally Posted by Barry I would run another set of strakes between the chine and the keel. The 773 was a three stage and the 212 has an impeller with a bolt on turbo impeller at the end.
Originally Posted by viking north Ha Ha --Tugboat just kiddin with ya on the similarities -- all them there speedy run abouts tend to look the same to us canvas men.
But my fav episode was the race that relic had with a prop driven high performance runabout. I vaguely remember , in fact an episode of it out of the water on a trailer I think being repaired and Nick Adonidas explaining how the jet pump worked to the landlubbers watching the show.
A lot of the research has now been superseded or is irrelevent, but some may just throw in an alternative thought. Maybe needs a touch more flare -tough issue for me ( - I'm from Va but went to school in NC ).
So I was thinking originally if warped it might run flat enough to be good if I stay out of nastier waves.
It takes more time and effort to go for this much detail in the software because each lap must be modeled individually, but it can be done.


The merc sj175 does offer a reasonable amount of thrust, but the downside is that in their infinate wisdom, Mercury put the exhaust from the engine in the cavity between the hull and jet unit. I tend to think of those that do as 'old school', and perhaps we should scrap the shuttle and fly the appollo missions again. As in aerospace, the trailing edges create a vortex, much like the tips of a wing, only in water that usually means that air is bled off, if that air makes it to the intake the pump will cavitate causing loss of thrust. Have owned jet boats since 1979 and built many commercially, but it takes these guys 3 months of training before they can take a paying passenger. Have owned jet boats since 1979 and built many commercially, but it takes these guys 3 months of training before they can take a paying passenger.****I hear ya, I have no experience so this would all be new to me but its on my bucket list. A 21 foot jet boat, including tanks would take about 20 25 hours of actual welding time, the rest of the time is fitting the plates, stringers, etc up. I would be concerned that the changes in length due to heating and cooling, ie different temp expansion rates between UHMW and fibreglass might be a problem. Actually Relic`s jet boat was a turn on for me especially `when the jump a log` stunt was performed. Looking at the forebody, it seems there is not sufficient cushion surface, neither a tunnel can help in a sharp bow configuration.
I have been a little harried with work projects, so I have not been able to do any work on updates. About the rendering, I can get a little top brisk in my quick sketches Do you have any advice from your WIG experience?
It needs to be hydrodynamic enough to get over the hump drag and get the body airborne so that ground effects can come into play.
I like the near-plumb stem, so kept that in spite of the lightness of the boat, since I'm not looking to go in big water. Hoping it might run 20-25kts with a 70hp OB, cut small steep chop easily off plane, and if lucky run comfortably at 15 or so.
As I remember, they are nigh impossible to get hold of (you may have to order directly if you can find the website) but they are well worth reading. If you have a 'rocker' the boat will bounce around, or porpoise, if it has a hook it will bow steer badly, possibly causing the boat to spin in a turn. Look at not only straight line performance, but also where any vorticied will end up in a tight turn (if you terminate your strakes ahead of the intake), if the unit cavitates during a turn and you loose thruse, a real nice jet spin often occurs, sometimes at an inconvient moment!!!
I beleive the class 1 boys use controllable vents in the wings, thereby reducing the pressure, bringing the bow back up. Feel over my head trying to integrate elemants here, but grateful for any constructive feedback. I would round the forefoot a bit, but easier to do in reality than in CAD, so it shows sharp in renderings. I prefer a multistage pump but Im no expert- it just seems running rapids you don't want to run a Berk or Jacuzzi. But I will say I have seen carbon fiber canoes hit with sledge hammers and nothing- and I mean not even a scratch happens.
Also, I remember a book called 'Dhows to Deltas' I can't remember who wrote it, but it has now gone out of print. Though I have access to a copy (for the next few weeks, so I'll have a look and post what I think may be useful.
Probably scan it and post it as a .zip file (the appropriate pages, that is, not the book).



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Comments to “Boat design website navigation”

  1. Dr_Alban  writes:
    Forward to construct my first boat this yr, have been performing some entire boat with fiberglass.
  2. ANAR84  writes:
    Particular order lovely sweep of the underside curve down from.