In looking at the designs on the French site - is it me, or do all of them have a lot of hull extending down below the waterline? A few of them seem to sit mighty deep in the water (hull - not keel depth).
Narrow hulls need more draft to get the necessary displacement. My No.3 (own design based on the Bantock Prime Number) has a draft of 40mm by 95 mm beam at the waterline (980g). My Laerke 65 has only 35mm by around 125mm (1050g) …
I went for the French Apsara cos it was the first one in the wiki list:lol:. Max beam is about 120 mm, so the rocker is bound to be correspondingly more. There’s no way it’s going to be able to carry excess weight, though.
I am thinking of a design first, with displacment to follow
Just keep adding weight until it floats where I want it to - or, maybe not.
Since some of the German “multihullers” are building foam hulls, adding a thin ply/balsa deck and wrapping the foam with plastic tape - I thought I would use their idea to build to a design, with ability to remove tape and modify - adding or deleting foam as needed. Thought the concept was a novel idea. Being of German heritage (1 generation removed) I can’t believe I didn’t think of that !
They do look ugly though - brown plastic packaging tape … but a quick way to see if design makes sense.
Hull number 1 (of four) was “splashed” last night. Dropped it into our utility tub. Boy are these sensitive to weight placement!
Didn’t have the keel on (naturally, since it has 13 inch depth) and boat floated well above her waterline. Placed the keel bulb in and shifted it around a bit (fore/aft) and does that ever impact the trim of the hull. Finally located and measured the location for the bulb which will be just a tad aft to insure a slightly raised bow when not sailing - and a bit of reserve buoyancy when hit with a gust and it goes “bow down”.
Still need to add epoxy fillets to all seams and around bulkheads where they meet the hull, cut a slot for keel and add the keel trunk. Then it will be a matter of keel alignment and epoxy of trunk. Keel will be removable.
Base lead bulb is shown in the photo below next to a marker for size comparison. Bulb is 16 oz. (1 lb. or 500 gr)
The build of a JIF.65 continues - with current/major emphasis on Hull #1 - as any mistakes (or education) will transfer forward to Hulls 2, 3, and 4! Besides, I have a grandson’s birthday target date to try to hit. Unfortunately he wants his painted, so the clear finish of the balsa will be reserved for one of the following hulls.
Photos of current progress to date.
Rudder has been shaped and has been spotted for final location.
Keel is cut, and trunk location has been determined.
Bulb needs to be attached, and entire keel give a layer of epoxy and glass.
Carbon mast needs to be cut to length and crane added
Sail that is visible is paper pattern. It has to be transferred to cloth, cut and assembled. I didn’t lay jib out, but it is also ready to go as a paper pattern.
On the insides - and not visible - the backing blocks for side shrouds have been added. All gunwales have had strengtheners added. Rudder log and block must be fabricated and added. Servo rails need to be fabricated and added. Then deck can be cut and fitted. Haven’t started on booms or any deck hardware as yet.
Thank you. I want to thank you as well for the plans that you made available on the web. Without them, there would be fewer boats built, and they simply are a “teaser” to want to build yet another design. I am currently setting up a building board for a round hull cross section and whether it is faster or slower - who cares? It will be a design that I like and will fit into the general RG65 rules so it can be sold and raced with few, if any, modifications. On the other hand, if faster, I will have relatives who may ban me from racing with them.
Thank you for making your plans available. If multihulls were allowed, I would be able to do the same.
Our informal association with the RG65 International Class Association has provided a great comparison of a few of the RG65 plans that are available. Below is copy of one such comparison from the RG site, which might help you decide on a specific plan for downlaod and build.
My thanks to Francisco Sampedro who is the RG65 ICA forum administrator for having posted the original.