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21 SC Main Trampoline installation
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Author:  Timd1966 [ Tue Feb 28, 2017 7:03 am ]
Post subject:  21 SC Main Trampoline installation

I have ordered a new main trampoline for my 21 SC. On this and other forums it has been said that I have to either mill a slot in the crossbeam or remove a hull.

I'd really rather not do anything that might affect the integrity of the crossbeam.

Looking at the boat, the main crossbeam is held in place by four bolts. Isn't it just a matter or removing the four bolts and lifting the beam up enough to slip the trampoline in the slot without having to take the whole hull off? (after I remove the mast and storage of course) If it is sitting on the trailer won't it remain stable enough?

I'd sure appreciate any advice from those that have done this.

Thanks,
Tim

Author:  M17FD [ Tue Feb 28, 2017 9:00 am ]
Post subject:  Re: 21 SC Main Trampoline installation

Tim,
Tim here. The great thing about the SC is you can totally take it apart to work on its pieces one at a time and/or for storage. So yes take the front cross beam off. You could use anything to wedge up to the hulls to stop any tilting left or right. I made fore and aft plywood cradles for mine that weren't perfect shape but with a little carpet between the cradles and hull it's great! Mine boat had silicone sealant around the bolts and bolt holes between the crossbeam and the hull. It was a total pain to clean it off the hull and crossbeam. Hobie suggests RTV sealant for this area but I'm a fan of buytl tape because it's flexible, easy to work with and never loses its elasticity/sealing power. Where are you located?
Tim
northern MI

Author:  Timd1966 [ Tue Feb 28, 2017 10:04 am ]
Post subject:  Re: 21 SC Main Trampoline installation

Thanks, Tim.

I'm in Sarasota, Florida.

My trampoline should arrive today. I also just received a power pole righting system - I mostly sail by myself. My plan is to install both this weekend. I'll look into the butyl tape.

Any other restoration projects/tips to share? I have a lot of work to do to mine to make it perfect.

Tim

Author:  mmiller [ Tue Feb 28, 2017 11:47 am ]
Post subject:  Re: 21 SC Main Trampoline installation

The forward tramp can be installed without taking the beam off. The tramp fits into the top (exposed) slot.

5. FRONT TRAMPOLINE INSTALLATION

Insert the forward trampoline into the upper groove of the front X-bar. The trampoline folds over the
front X-bar and then inserts into the forward trampoline track. Slide the tramp track forward (leave
loose until cat cabin is fully installed). After the cat cabin has been fully tensioned down...pull the
tramp forward until taunt to slugs in forward spreader bar.

http://static.hobiecat.com/digital_assets/21SC_Manual.pdf (page 5)

Author:  Timd1966 [ Tue Feb 28, 2017 6:31 pm ]
Post subject:  Re: 21 SC Main Trampoline installation

Thanks, Matt.

I was referring to the rear trampoline, not the front one.

Do you think I can just remove the front crossbeam and install it with out trouble? If so, why have people advocated for milling a slot or removing the hull which sounds like a lot of trouble.

Tim

Author:  srm [ Tue Feb 28, 2017 7:04 pm ]
Post subject:  Re: 21 SC Main Trampoline installation

As far as I know, the 21SC uses the same front crossbar and attachment method as the Miracle 20. There are threaded aluminum bars bonded inside the hulls that the front crossbar bolts screw into. Since the bars are aluminum and the bolts are stainless, there is a good chance that, over time, the bolts will become seized (galvanic corrosion). When this happens, it can be a bear to remove the front crossbar without damaging something. That would be my guess as to why some folks have recommended milling a slot to take off the tramp rather than trying to remove the whole crossbar.

sm

Author:  mmiller [ Wed Mar 01, 2017 9:47 am ]
Post subject:  Re: 21 SC Main Trampoline installation

Timd1966 wrote:
Thanks, Matt.

I was referring to the rear trampoline, not the front one.

Do you think I can just remove the front crossbeam and install it with out trouble? If so, why have people advocated for milling a slot or removing the hull which sounds like a lot of trouble.

Tim


As I seem to recall, later Sport Cruisers had a slot milled in the track for the main tramp, so yes that is an option. I can't confirm that on the drawings I have, but totally makes sense.

Author:  Timd1966 [ Wed Mar 01, 2017 11:14 am ]
Post subject:  Re: 21 SC Main Trampoline installation

Thanks, Matt.

Mine is a pretty early one. 1993: sail 108. There is not a slot milled in the crossbar.

Do you, the architect of the boat, recommend unbolting the crossbar or buying a dremel and milling a slot.

Of course, I take your advice altruistically and will in no way attempt to hold you accountable for any mishaps.

If it looks like I need to mill a slot, any tips or advice? Anyone? How big of a slot? - What bit?- Etc.

Tim

Author:  mmiller [ Wed Mar 01, 2017 11:45 am ]
Post subject:  Re: 21 SC Main Trampoline installation

I would get a dremel and mill a slot at one end of the crossbar against the inboard side of the hull. The risks related to disassembly are far greater.

Author:  M17FD [ Thu Mar 02, 2017 9:25 am ]
Post subject:  Re: 21 SC Main Trampoline installation

For me, Tim, taking off the cabin and the crossbeam(s) has been an easy job and necessary for the restoration I'm doing on mine. Take a look at these dudes and this crazy trip on stock 21SC's just like ours. They totally took their boat apart for epic portages etc. They also made custom protective bags for each hull for truck shipping the disassembled 21SC. Very cool boat Matt Miller designed!!
https://www.flickr.com/photos/betopandi ... 68671/show

Author:  Timd1966 [ Mon Mar 06, 2017 6:12 am ]
Post subject:  Re: 21 SC Main Trampoline installation

Those are outstanding photos. It's always great to have some inspiration.

The trampoline install went off without too much difficulty.

I don't know how many times I have to learn this lesson but...I didn't buy a Dremel, I purchased a knock off from Harbor Freight for a fraction of the price thinking that I only needed it do do this one job. Heavy sigh. I broke most of the bits off almost immediately and even damaged the shaft that the cutting discs went on. I ended up borrowing a quality metal grinder and then using a polishing bit to smooth the edges. Anyway, I know have a one inch, smooth slot off to the side of the crossbar and a new trampoline. I also installed a power pole righting system while I had the trampoline off.

Author:  Myke [ Wed Apr 12, 2017 11:20 am ]
Post subject:  Re: 21 SC Main Trampoline installation

Timd,

PM sent.

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