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Calm Spirit's Zip under way

Posted: Sun Jun 17, 2012 2:18 am
by keithhills
Two weeks ago I started construction of a zip to be used as a new tender for Calm Spirit.
I have been busily building the frames this week, and because this is virtually a utility with no cross bulkheads I have been keeping the knee joint supports as small as possible.
Lying in bed this morning and thinking about the project I became a little concerned about the size of the knee that I put between the horizontal and vertical members of frames 2 and 4.
Being an open utility there is no deck member to give extra outward support. I have made the 1/4" ply 6" high as the drawings show and epoxy glued the parts together, but obviously I don't want a problem later.
My thought is to put 1/4" ply on both sides in addition to between the members.
I would love to hear the thoughts of those who have finished their projects.
Have a great day, from Australia.
Keith Hills

Re: Calm Spirit's Zip under way

Posted: Sun Jun 17, 2012 6:00 am
by Roberta
If you haven't glued up the joints, why not cut the joints and use the newer joint style described in the plans. That style uses plywood on both sides of the joint. I think it will be hard to slab over the present joint. Using the style you have used, lost some strength because you trimmed away so much of the gusset.

Roberta

Re: Calm Spirit's Zip under way

Posted: Sun Jun 17, 2012 6:12 am
by Andy Garrett
I think your concerns are valid and may need addressing. You never want to ignore your gut instincts.

Looking at your joint there, I see a bolt which provides a pivot point and only two screws (and glue) keeping it from folding up. This gussetted lap joint is the minimum standard called for in the Zip plans and it prefers more of a gusset where yours is trimmed away to provide a more open hull. This might work in a standard Zip with a deck, but with yours foregoing the cross members and decking, you may indeed have a weak spot in the design.

I would opt for a stronger joint here rather than a minimalist one, knowing that I was going to have a very open utility hull.

Then again, I don't know what kind of stresses your Zip will endure as a tender to a larger vessel.

If it were me, I'd add ply or scrap frame stock to my exposed gusset on both sides until it was level with the frame on both sides. Then, I would double gusset the entire joint in 1/4" ply on both sides. This would raise your strength level to above the strongest recomended design (double gusset), by making it a true 'triple' gusset. It would also be the easiest and quickest fix while compensating for the lack of deck frames.

You'd end up with a very strong laminated joint at 2 1/4" total thickness. That's a lot of material for your chines to get good purchase as well.

That's just my two-bits. :wink:

Re: Calm Spirit's Zip under way

Posted: Mon Jun 18, 2012 6:11 am
by keithhills
Thanks guys. That confirms what I was thinking. Like you said, go with your gut feeling.
I will do it tomorrow before I epoxy coat all the frames.

Another question: how do you put a photo signature on the left of the screen?

Re: Calm Spirit's Zip under way

Posted: Mon Jun 18, 2012 6:30 am
by BruceDow
To add a picture or "avatar:....


In the upper right, click "User Control Panel"

Over to the left, click "Profile"

Over to the left, click "Edit Avatar"

follow the instructions to attach a picture from your computer.

Re: Calm Spirit's Zip under way

Posted: Wed Jun 20, 2012 12:21 am
by keithhills
I am up to fitting the chine and have found that to sit into frame 5.5 I need to twist the chine timber, then when I get to the stem the timber needs to be twisted in the other direction.
Is this what you experienced zip builders found and how did you take the tensions out of the timbers?
I am now 64 hours into the build over the last 3 weeks and having a great time. I will throw in a photo of where I am up to as well as the detailed chine photos.
Have a great day.
Keith

Re: Calm Spirit's Zip under way

Posted: Wed Jun 20, 2012 5:09 am
by Roberta
I had exactly the same twist in my chines. I wrapped the chines in wet towels and poured boiling water on them and also used my shark steam mop to help twist them. Make sure you leave a few inches of chine back by the transom. That way if you are not happy with the cut at the stem, you have some material left to recut.

I also found it easier to start the chine bends at the stem and work my way back to the transom. You do need a lot of room to do this as the chines are very long.

Roberta :D

Re: Calm Spirit's Zip under way

Posted: Wed Jun 20, 2012 8:20 am
by Iggy
I also found it easier to bend from the stem backwards towards the transom. When I did it the other way around I ended up snapping the chine during fit-up.

The twisting is a bit unnerving at first, but it works.

Re: Calm Spirit's Zip under way

Posted: Thu Jul 05, 2012 9:38 pm
by piobaxter
Wow. please post if it is already finished.

Re: Calm Spirit's Zip under way

Posted: Sat Jul 07, 2012 1:14 am
by keithhills
Still working on the fairing of the starboard side. Made and installed a side frame between 4 and 2, and also between 4 and 5.5. Because my boat will be a utility without much of a forward deck I positioned the frames at the back of the seats and as a mini bulkhead at the aft of the centre consul. I have attached a drawing of what I am envisioning.
The idea is to help form the ply and also give added strength considering the rougher conditions that I may encounter in our boating.
Making up a frame for fairing without a drawing is an interesting challenge, but very do able with some thought.
Hopefully tomorrow I will get all the fairing finished on the port side now that all the gluing is done.
You may also notice that the outboard is set in. I had to do this to keep the overall length within the length of the boarding platform on Calm Spirit. Another interesting challenge, but one that I think has worked OK.