Location: San Francisco It looks like a piece of crap with negative value, to me. The keel is weirdly tiny, and it looks suspiciously like someone has hacked out part of whatever it was made of first and replaced it with a hunk of lead(?) in a (probably hopeless) effort to make the thing stay upright. If it had actually sailed at one point in its life, it might be a fun project to bring back to life -- still a big financial loss, but educational and fun if you're in to that kind of thing. Location: Cathlamet, WA It looks like it could be a John Brandylmeir (sp?) design. Location: San Francisco Out of curiousity, what makes you think it's a Brandlmayr design? I poked around, and all the designs I found seemed to favor a more traditional sheerline and rather more rake to the stem. Location: Cathlamet, WA While sailing near Campbell River about 35 years ago a 24 foot sailboat designed by Brandlmayr sailed by us quite handily on a similar sized boat. ISO and GL » Thread Tools Show Printable Version Email this Page Display Modes Linear Mode Switch to Hybrid Mode Switch to Threaded Mode Search this Thread Advanced Search Similar Threads Thread Thread Starter Forum Replies Last Post Through-hull for steel sailboat - how to do it ? When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Location: Scotland S70 Project (Give your ideas) This is what I have so far for my teams strathclyde 70 class hull. Location: Scotland Rig Design Heres a quick collage i made in photoshop. S70 Alex, I can't open your pdf file on the rules since I have webtv so I can't comment on how well your boat may fit those rules.
2) google Lester Gilberts technical site-primarily on IOM's but full of usefull design information for RC model Yachts. Location: Maine Alex, the first drawing you posted seems to have a lot of things cluttering up airflow in the rig.
Personally, i would suggest looking into a sloop rig with a large roach mainsail and moderate roach jib. Location: Scotland Yes ive looked at that thread before but it takes some reading and for some of us lesser educated people it is quite tough going.
Also on the subject of hulls would there be any point in making the hull in the shape of a symetrical airfoil. When at rest, a surfers weight is borne entirely by the buoyant force (also depending on how much beer you drank the night before).
At low speeds every hull acts as a displacement hull, meaning that the buoyant force is mainly responsible for supporting the surfer. A fluid flowing (water) past the surface of a body (surfer + surfboard) exerts surface force on it. In contrast, the buoyant force decreases as the hull lifts out of the water decreasing the displaced volume.
This is the reason that surfboards with lots of rocker need more speed and their no rocker cousins scream across the water. The major difference between a planing surfboard hull and a displacement hull is the way in which the surfboard travels through the water. At high speeds a displacement hull’s tail will sink down lower and lower as a result of the “hole” created in the water as the surfboard moves forward.
A planing hull, on the other hand, will have a flat or concave bottom contour and plane up on top of the water.
Displacement hulls push through the water as they have no hydrodynamic lift, or the surfboard does not rise out of the water as speed increases.
The hull design (shape) does not limit the maximum attainable speed but does affect the power required for it to get on plane (on top of the water). Semi-displacement or semi-planing hulls have features of both planing and displacement hulls.
There is not one hull design characteristic that differentiates semi-displacement from semi-planing hull.
The greater the hydrodynamic lift and higher the hull design speed the more likely it will be referred to as a semi-planing hull.
I came across this blog post by Steven Mast of Mast Surfboards and it is an excellent discussion of the topic.
Old, soft edged boards are the same, as are any true displacement hulls being produced today.
Now I’m sure I’ll get some flak for this, but displacement hulls, by their very nature, are not as fast as planing hulls (editors note: .
Another thing I’ll take flak for, and I’m saying it anyway, Greg Liddle did not invent the displacement hull surfboard.
All displacement hulls, although arguably not “modified transitional displacement hulls”, whatever that means. I (even after researching and writing it) have to reread it sometimes to understand it too. I am totally with you on this, my experience is that a board reacts differently in a turn vs. Putting an edge on a tail does not automatically turn the board into a PH—totally agree. All surfboards (regardless of the intentions, theories, or fantasies of their designers) plane on the wave face.
Most simmons hulls I see are single concave, but I spoke to a guy in the water who was riding one with a v hull.
Location: Venezuela boat hull design (pad design) Hello, my name is Cristian,this is my firth time here, and i would like to know somebody hellp me.
I have a powerboa 16? vee fiverglass 22? 140hp looper, and i like to put in it a pad but i don?t know the dimensions (size), and how it comport in the boat, i have very much time driving boat, but never with pad, and i need the pad for more speed and woul like to know about the size of a box of water that the people do for blow off in final of transon and bow. I'm not familiar with the calculations for retrofitting an existing hull with a pad; most boats I see with one have it built in from the start.
Location: Venezuela thanks matt, bu i like to know what is small size in inchs.
Originally Posted by solrac hi guys, I'm a kind of a newbie to al this concerning to design of a 30" sailboat.

Location: lithuania Nice job, although I didn't like the shape of the hull. The best results I've got in modern sailboat hulls is to use 3 x 3 control point surfaces and changing the point weight to get the shape, LCB and prismatic coefficient right. Location: santo domingo, dominican republic Why two set of runners on each side? Location: lithuania I would rewove one of the rear bunks with cocpit loker, it would make sailing a lot easyer, because, you always have a lot of struf on an ordinary cruiser. If you still want to keep those racy sheeting angles you could put the tracks on the cabin top. I'll work on the steering mechanism (don't you think a wheel will reduce too much the cockpit space?) and the engine. Location: lithuania steering weel uses less space in the cocpit than tiller, you need a lot of space to turn it, and if you are sailing with friends free space would probably be hard to find , and mounting autopilot system (which might be very usefull for sailor like you) would be simplier to.
Originally Posted by tamkvaitis steering weel uses less space in the cocpit than tiller, you need a lot of space to turn it, and if you are sailing with friends free space would probably be hard to find , and mounting autopilot system (which might be very usefull for sailor like you) would be simplier to. Would this vessel have to be a hydrofoil or multihull, or could a monohull with a hinged transom of sorts convert a double ended full displacement hull to a squared off planing hull? Location: Australia Displacement-type cats probably the most likely candidate for a boat that can operate efficiently over a wide speed range.
Location: Australia If such things were easy, or practicable, or affordable, they would have arrived on the scene by now. Location: NW Washington State USA One way to do it would be to hull a bit like a Handy Billy that at a bit less than hull speed would have her transom out of the water and present an excellent full disp hull form to the water.
Location: Sweden As far as I've understood there isn't really a maximum (displacement) speed for long and narrow hulls. The performance of any boat, and especially a multihull, goes out the window if you overload it. Location: Everson, WA From the thread, I am leaning t'ward a catamaran with hyper narrow, deep hulls.
Location: Australia There is no miracle design that will do everything better than all others.
The subject of efficient power boats interests me, especially in the 10 ? 20 knots speed range. If fuel efficiency is the only criteria and length is not a restriction, a long and narrow monohull is the answer. A conventional trimaran has stabilizing amas that extend outside the sides of the hull proper. Another variant on the stabilised monohull theme is the displacement glider, also called box keel boat. The underbody just looks wrong, and in the absence of evidence to the contrary, I think it IS just wrong.
We will probably make a second boat with the same hull but with single rudder and bermuda rig to test again. I wanted to try and get any sails behind the mast away from it so they get less turbulent air. This design does not ride high on the water like a planing hull, instead plowing through and parting the water. There are displacement hulls, planing hulls and as usually is the case, some variant of the two. The very nature of the release provided by that edge, by definition puts that board into planing mode. As soon as they get going, the tail end of the board starts submarining and they can literally walk to the nose and go.
As soon as you put an edge at the tail, you release the water and the board begins to plane.
They may “feel” faster in a section, but without the release, they are constantly dragging more than a sharp edged board would.
He refined it to an amazing degree, made it work in a short package, championing it when it was completely against the trends of the time, but have you ever seen a Weber Foil?
But i still don’t understand the general accepted theory that as soon as you put an edge on the tail it turns into a planing hull. This will prevent the mainsail to open freely when running, and will add up to more work, which can be a burden when short handed.
From the line drawing of the sections it appears you have some major localised flat spots, hollows and maybe even creases.
The rig could lose the runners for your style of sailing, maybe a running backstay for mast bend and a baby stay to stop the mast from pumping.
This design uses stering system similar to stering with steering weel it is dificult to see, the ruder is in front of the tiller! I've seen the HYSUCATs, and would like to get feedback on a trimaran (HYSUTRI?), or another hull design. Transom extensions might make some theoretical sense, but in practical usage, transitioning from one mode to the other, on water, would likely be problematical. But because of her rockered bottom w more power she'd pitch up, squat a bit and have a submerged shape much more like a planing hull and go gracefully at speeds much higher than disp.
I guess that this is because it is easier to make a practical boat with a catamaran hull than with a trimaran hull. Ultra narrow catamaran hulls might be attractive for their minimal wave-making resistance, but cause hobby-horsing running into a sea, as well as being very sensitive to fore-and-aft weight distribution. I estimate that the boat that fits my requirements has a displacement around 4 tons, so I?m looking at long and narrow hulls used in displacement mode. The platform connecting the two hulls needs a clearance of half a meter or more to the water, to avoid waves slapping into the platform. This arrangement complicates handling in harbours so I?ve ruled out a conventional trimaran for myself.
The box keel provide maybe 80% of the buoyancy, provide standing height in the forward cabin and can accommodate engine, fuel, water and technical installations. My hope is that such a boat can be made in the spirit of the beautiful power boats designed by CG Pettersson during the first half of the 20th century.

Neither the service provider nor the domain owner maintain any relationship with the advertisers. I'm a cabinet maker by trade and not a boat builder but this looks like a well built hull and deck that I am considering picking up and working on but no plans are available and the original builder has passed away so there is no information available to me as to the design.
It contrasts with the drag force, which is the component of the surface force parallel to the flow direction. Think of an ocean liner moving through the deep ocean versus a speed boat racing around a lake. The modern surfboard, most “hulls” included, balance these principles to achieve the desired effect or feel. On the contrary, I think his boards are brilliant and have been a huge design influence for me.
A displacement hull works more by pushing the water around it’s hull and through the rails and tail, where as a planing hull works more by channeling the water directly through the hull.
Put the spoon face up (like a v-hull), and the curvature of the spoon allows it to wobble effortlessly. I have seen prety nice removable and rotating stering weel systems, so it can be removed or rotated, to minimize place required. A tri could cruise on a small diesel in the center hull and have big block chevrolets with jet drives in the outer hulls.
Hydrofoils sound great, until one hits anything more solid than a duck and somersaults into oblivion. Gracefully that is excluding the fact that her bow would be ungracefully high in the air, subject to winds that could make a mess of directional stability.
From boat data I've seen, and my own calculations using Michlet, long and narrow hulls are used at speeds up to around 20 knots for a 12 m long boat. I wouldn't count out a mono-hull Tlinget or Otter types either (people in the Northwest will know what I'm talking about). If you also want a useful boat, a monohull has to be considerably longer than 12 m to provide an acceptable beam.
Anything you build on the platform will have quite a high CoG so you will need a minimum total beam for the catamaran of 3 m - 4 m for stability and to avoid excessive wave interference between the hulls. The clearance to the water for the hull spanning the distance between the main hull and amas still needs to be around half a meter with resulting high CoG. In case of trademark issues please contact the domain owner directly (contact information can be found in whois). Its a little hard to start talking to people about rigging without knowing what to call her. Also would it be better to have the servo attatched directly to the mast in a wing sail design. A displacement hull has a theoretical hull speed, above which the water actually sucks the hull deeper into the water (I’m simplifying here). The feeling of a well balance hull is one of the great pleasures of surfing that most people fail to credit. A small amount of edge in the tail of a displacement hull will not convert the entire board, it will still act as a DH. And I would try to move the engine as far aft as posible (I like dashev concept) It would make a lot of space inside. The idea would be to waddle along at single digit speeds for maximum range, then roar over the horizon when the Somali pirates show up. First hand experience with a planing hull at displacement speeds proved to me that just pulling back the throttles does not save much, if any, fuel. Michlet is based on theories for wavemaking that is applicable for long and thin displacement hulls and consequently is most relevant when wavemaking is the major resistance component.
My search is for the hull(s) design that goes the fastest with the least power, then I can work on a compromise of accommodations, tankage, complexity, initial cost vs long term cost, etc.
For adequate initial stability, the total beam needs to be more than 3.5 m for a 12 m long boat. Surfing one well takes a different approach, especially if you are stepping off a thruster. If you were going for a hard back foot turn with little else board in the water than the tail only then you could call that planing, otherwise it would still feel and act like a DH majority of the time. Actualy you should look more on th dashev boats, thay look (I have not sailed any) great sailing boats, with huge amount of comfort. With an open transom like this it is much easier to access the boat trough the transom from a dinghy or pontoon than with a wheel.
If you go for planing multihulls you will sacrifice efficiency at low speed for a higher top speed, but the low speed efficiency might be adequate for your needs anyway. The data LWL = 20 m, BWL = 2 m, draft = 0.5 m, displacement 12 tons approximately describes the minimum useful displacement for a monohull (for speeds around 15 knots).
At anything above the theoretical hull speed, the boat begins to submarine, actually being pulled deeper into the water. If you transpose the outline of the cabin on to the layout plan you will see that above most of your seating areas you have little or no headroom and no shoulder room or full headroom in what I think is the head. A trimaran would have room for an engine in each hull, max range in the center engine, max speed with all 3 engines, and something in between on 2. It sounds good until factoring prismatic coefficients (and other formulas naval engineers have a total grasp on) for different speeds. A wise man once said the most efficient way to go through the water is not to go through the water, but the air instead, with as little of the boat in the water as possible. I have had a bit of change of thinking about this recently, and will shortly be testing a new idea via some scale models, if it's got legs I'll post some news. The boat I have experimented with is unfortunately a bit too heavy to get a good response from, with the air cavity size it has.

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