Hull Curve

[Brian Paton]

I notice there is a curve on the hull of the Pahi and Tiki designs, can anyone tell me if this curve has been added to the classic designs. (Tehini).  I have the study plans for the Tehini and it shows the bulkhead profile as having straight lines and no curve.  I have emailed Wharram but can't get a response.

 

Brian

[Iain & Cherry Mae Cairns]

Good day Brian, I have checked the sides of my boat with a straight edge, & yes they are straight, just like the study plans. hope this helps. Although mine is probably one of the older plans, not sure if they have altered the newer plans. 

Iain

[Joe Swetish]

I have a recently purchased (2009) set of Tehini plans, and all of the bulkheads are straight.  An Ariki recently presented by Boatsmith had been updated to have some camber in the sides of the hull. I don't know how to post links, the photo is on page 7 now, named "100 2416." I'd like a hull with some curve to it, it should stiffen the overall structure.

Question for anyone in a position to know: Would this be a simple process to add some curvature to a straight V-hull, or would it involve an extensive and complicated lofting process, and in the end be more trouble than it's worth?

JOE

[boatsmith]

Joe, The Arriki we are building is being built of foam cored glass. The slight camber we introduced makes for a stiffer skin. This allows us to reduce the amount of internal framing and stringers. The photo you have referenced is of the mold for this boat. It would not be possible to build this shape from sheet goods. Part of the beauty of the Wharram designs is that they are able to be built of sheet goods and this makes them much easie rto build. We will have about 400 hours into this mold before  we are ready to lay up our first hull. We are spending a lot of time fairing and tweaking to keep the same flavor as the original Ariki while optimizing it for glass construction. Lots  and lots of long boarding. Then when we pull a hull from this male mold we will still have to fair the outer skin before paint. The  plywood Tiki 30s has a very minor amount of camber built into the hull; about 15mm if I recall correctlly. The Tiki 8m on the other hand has about 50 mm.   David

[Brian Paton]

Thanks everyone.  If I want this camber added will Wharram do it or will I have to go elsewhere.

[boatsmith]

My guess is elsewhere

[Iain & Cherry Mae Cairns]

yea my guess as well , ELSEWHERE.

 

[Omar M. Rashash]

When you start making changes in the shape of a stitch & glue plywood hull, it's like working with a bowl of spaghetti, you pull one strand, it moves elsewhere.  At the very least, if you put a curve in the bulkheads, and camber in the sides of the plywood hull, you'll make changes to the shape of the sheer line.  What you may discover is that you've created a shape that can't be covered with tortured plywood.  Too many conflicting curves to get the plywood to lie down properly.

 

HTH,

Omar

[Brian Paton]

I plan on doing what boatsmith are doing and make a mold.  I then plan to resin infuse the hulls.  So I'm not interested in the plywood lying flat I just want the hull form with the camber.

[Martin Phillips]

 I think that before I select a design to pour my hard earned cash and year's of labour into building I would ensure it was the boat that I wanted. Why choose a Tehini if you want to change something as fundermental the hull shape? The design is now very old but why not go for the Tiki 46 which basically does the same thing - 8 berth plus ocean cruiser - but how James and Haneke saw it 15 years ago (and 25 years after the Tehini was designed). It has rounded V hulls as you want and a far better use of space. Its a much more sophisticated boat but still has that unique Wharram style that appeals to us. A rounded V is still a V shape. Richard Woods designs monocoque ply wood/epoxy  designs with multi chine hulls rather than V shape and so does Peter Snell.  Derek Kelsall has flat panel and rounded hulls in GRP/foam sandwich including open deck options and very simple construction. There are also the Simpson designs from Botecraft to look at My feeling is get the design you want to build rather than mess about modifying an old design. Like you I would be inclined to go for GRP foam sandwich so I'd think quite seriously about the Kelsall flat panel hulls. In fact I guess you could make KSS panels to replace the ply sheets used in any Wharram design but I am afraid my gut reaction is that once you modify the design you end up designing a new boat. A good example of doing this and retaining the Wharram design is Natural High. But you need a good builder/designer to do the redesign who knows GRP construction and ensures that the strength and stress management inthe Wharram wood design is replicated. Otherwise the result may look like a Wharram but as so many modified efforts have proven it will lack design integrity and be a disaster. Unless you are a designer (in which case design your own boat from the start) I would not spend loads of money buying Wharram plans to mess about withit so much that the finished boat is not a Wharram design at all. I think there are too many examples of that! Its so nice to see boats built to plan that are sucessful - Pilgrim is a superb example. Love the video! However watching that make me think whether a monocoque cat with a bridgedeck cabin and protected cockpit is a much more comfortable vehicle to sail. You choose your design and take what you have chosen I guess.   Me of course - I sail a very old vintage boat and love it because it is a classic. I love the Tehini for that reason. But when it comes to choosing my next boat I may put practicality ahead of sentimentality!

[Brian Paton]

Why do people customize cars, buy a new home then change the kitchen, design a new shape of garden.  Some people want something different.  There are still plenty of people that love the classic design shape but want to improve on it.  With modern high strength foam and infusion processes you can make a product that is just as strong if not stronger.  I've seen pictures on here of boats that have a complete bridge deck added.  Why not go for a Kurt Hughes boat or Gilbert Caroff.  Aesthetic appeal comes in here as well.  I think the Kelsall cats look like floating caravans.  On another note Wharram also moved on by designing the Tiki 46 and charging more for the plans.  The classics have taken a back seat.  Why waste time improving older designs when you can just design a new boat.  He is using his creative mind and so am I.

[Martin Phillips]

Customizing and personalizing are OK in anyone's book. Changing the basic design is a different matter so adding bridge decks and changing the hull shape in my mind changes the boat so it is not a Wharram because quite simply it becomes your design and not his. Anyway its a free World and obviously Wharram does not license his plans like designers such as Brown/Marples or Simpson so that you can only change it with his consent. I guess in the self build business that invites people to tinker and produce something the designer never intended. Trouble is it also gives the designer a bad name because people look at these creations and say "look at that Wharram" and "it is so ugly" or "isn't that thing pitching like crazy" "or I'd never have one of those" when if they saw a lovely vessel built as it was designed they may be very impressed with the design.

Personally I love Wharram's designs but I cannot say I love all of the boats I have seen apparently based on his plans!

I am sure that with the good advice you can get on this site and good sense of  either going to Wharram or another designer to get them to professionally modify the plans to get the boat you want,  you will build a beautiful seaworthy boat!

Best wishes and good luck mate!

[Tom]

LMAO at Chuck.  Cheers about the ex haha

 

Brian, as a ship builder you have a responsibility to every person who may ever set foot on the vessel.  Don't fuck it up.  Don't get anyone killed.