Tiki38 hull "wobble"

ADVERTISING
LINKS

	Tiki 38 Hull "wobble" (during build), e-mailed to Scott
	Question from builder Ran ~ do the little wobbles come out of the ply when upper panels are joined? we thought the stringer would take them out when we used pipe clamps to get it straight ! Builder Dave ~ Wobbly ply on lower hull. ( I should explain that "wobbly", in the case of my boat, means bulging outwards just aft of bulkhead 4). I don’t know if this helps but..... I had considerable "lining-up" problems when dry-fitting the ply panels which resulted in my being unsure of the correct shear for the chine. My solution was to fit an extra internal stringer at the chine position so that I could trim the panels to the stringer after turning the hull. [Similar mod. has been included in the building instructions for the upper hull]. This method means that I did not fit the external stringer until later. The panels were still "wobbly" even after fitting the external stringer whilst pulling the chine into a fair shape. However, keep pulling the chine into shape while fitting the floors and bunk in the main cabin and it should be OK. I’m sure that the internal "furniture" that goes in, before you get as far as fitting the upper panels, will help correct this problem.
	Builder John ~ I assume from that small snippet that you are being asked about the ripples in the lower hull panels at the chine line. Yes.. If he uses clamps and holds everything in the right place before gluing in the furniture then once the furniture is in place the ripples in the chine should come out. I am not sure if there is any mention on the plans but after one of Hanneke’s visits it was decided that the lower hull panels should be put on one at a time. That is.. don’t glue two or more sheets together on the floor and then put those on. It was also thought prudent to actually cut a curver in the ends of the plywood sheets being used for the hull panels to try and remove some of the excess meat you have when trying to curve plywood in multiple directions. This is done by cutting the hull panel per plan and then on the ends of each sheet make a curve with the outside edges approximately 5 mm shorter than the centre. This means when you glue the sheets on and curve them hopefully you in effect get a straight line up the hull side Builder Dave ~ Glad to hear that John agreed about the hull furniture holding the hull in shape. His comments about the lower hull panels are VERY interesting because it is at the stem and stern that most problems arise when trying to align the panels (see my reply to Ran). Putting each panel on separately would help. Curving the end of each sheet might make things easier as well. I haven't been given any info on these mods by Wharram Designs, although I have discussed problem with John Barker. My solution is: don’t loft out the panels as per plans and expect them to fit (too many possibilities for error), but make patterns from the hull - that way they MUST fit. I believe their new designs are using a similar method. Ran ~ Jan Gougeon flew in today in his rv4 plane that he built and looked at the progress. Says he likes the way it is going together, looks very strong. He thought that clamping a large plank below the stringer should take out the wobbles and would hold it till bunks and topsides are in place then it should stay out................... It worked! the wobble is gone. In fact, after reading johns email I fear we may have caused it. Eric likes to have things fit as if they grew that way and there wasn’t any gap at the ply joint. The next hull panels we will make sure there is a gap and see. Probably next week we will be putting panels on the other backbone.
	Ran again ~ well here is a picture, seems difficult to see or photo. between bulkhead 4& 5 the side bows out and in and again between 5 & 6. I clamped the pine board you see in the picture to the side and it took the wobble out between 6/5 and almost all between 4/5 it is only a 1x10 southern yellow pine I think if it was a 2x 10 it would have solved the wobble and after the bunks and side panels are on it would stay out. if it does we’ll drill a couple holes and with backing blocks and bolts pull it in till curve is fair and leave it until deck is on, then remove it and patch the bolt hole, I do like this epoxy stuff!

This page was last updated on 06-Sep-2001 .

Multihull Forum