Tiki 21 rear trampoline

[Ian Bamsey]

I'm fitting a rear tramp to my Tiki 21. I want to maximise the available space. I've tested a fibreglass windsurfer mast as a support pole. It only deflects about 25cm with 80kg point load in the middle of the span. It's only 52mm OD, excellent!

The question is how big to make the tramp?

How far should it go back. I've seen few short ones and some longer, but what are the pro's and con's? Who has experience here who can provide some useful input?

Ian

[Rory McDougall]

Hi Ian,

You don't have to use a beam if you don't want to. I have used a stout rope across the sterns to hang the net on and has worked well. I went right to the tips of the sterns with the net and it creates a perfect space to stow the rolled up inflatable dingy when underway.

See pic below. Cheers Rory

[Ian Bamsey]

Thanks Rory, I guess you qualify as having some experience on this one! So I have my answer.

Can you help with on more question? I'm still trying to work out the best way to arrange a mooring bridle etc. The current arrangement uses a heavy rope and clutters up the forward beam end cleats. You can see it hanging down in the picture.

When the boat goes back in after its refit, it will be on a mooring at Starcross. I need to be able to connect with my pick up mooring easily. You have fairleads and deck cleats, but my decks are not strong enough for that. May be I can bolt extra cleats on the forward beam and have a lighter weight bridle.

Thanks for any input. What would you do? 

[Rory McDougall]

Hey Ian

You could still use the cleats on the end of your fwd beam and add fairleads to the inboard end of the bows. I have Cookie on a mooring off Lympstone and have a bridle on top of the riser chain. I have a pickup buoy attached to one of the bridles. The bridles are 12mm multiplat with plastic hose sleeved on where they go through the fairleads - so no chafe at all. Very simple and works well.

Cheers, Rory

[Ian Bamsey]

Thanks Rory, most helpful. Do you therefore carry another bridle for mooring / anchoring elsewhere?

[Jay Bennett]

Good timing to have a discussion on the rear tramp as I too am currently planning this. 

I have been thinking to run a 100mm diameter length of carbon tube along the rear in front of the rear "handles" to the front of the rudders (maximising available space as I do not think weight is going to be an issue  with centre balance point).  I am looking to create a boarding/ swimming ladder I can lower off this to one side of centre leaving a trampoline over the rest ( hence the 100mm dia.). We sail a lot with our dog and so need to make a ladder which he can climb back on after a swim - hence a simple rope ladder doesn't quite cut the mustard. 

And we still want to leave enough room to run a self steering system using an electric self steerer and rope and pulley system. 

Initially I was planning to create a bike rack in the rear area as we have quite a few mountain bike tracks around Lake Taupo which do not meet up and require boat access. I had thought I would run the 100mm tube and place a couple of wheel clamps on the rear beam; but then this really restricts the movement of the mainsail so have decided the best way to carry the bikes is in a bike bag lying on a rear tramp. 

 

[Jay Bennett]

Ian in regards to your questions about a mooring bridle. 

Our tiki has two 50 to 70 mm "U"bolts which go through the front of each hull from side to side - the cable to attach the forestay is attached to these. 

We attach our mooring line to these u bolts with stainless carabiner clips and a stainless swivel to attach to the mooring float in the middle of the line. I can take a photo tomorrow when i am on board. 

This works really well and has proven itself in some major storms. 

Simple and easy to use. Also provides a quick and easy attachment point when we sail onto a beach or need to anchor. 

[Ian Bamsey]

I looked into using a carbon tube. The deflection was too large unless I went for a bigger diameter, like 100mm. I was pleased when my brother gave me an old windsurfing mast. 50mm diameter and about 200mm deflection with 80kg point load in the centre. The mast has an internal structure and is very stiff. I prefer a smaller diameter to keep the profile down where it sits on the stern decks. I'm planning small pads epoxied to the stern to seat nylon tube inserts. The inserts will have flat on one side to sit on the pads and a small groove to locate the lashing cord. I will lash the tube down (like the Tiki beams) to small vertical pads on the insides of the sterns. The picture below show this arrangement (badly).

How do you plan to mount your tube?

Also, Rory's got me thinking. What exactly is the advantage of the tube over a "stout rope"? It would better distribute the weight and might allow a mesh type tramp to keep a better shape when walked on. My main purpose is to provide more space for small boys to explore and provide a fishing platform. It will allow a dingy to be carried without using the front tramp.

Thanks for your comments on the anchor/mooring question. And let's have some more pictures of your boat!

Ian

[Roger]

I'm with Rory -  a rope works well. On Little Cat, I keep the rope tensioning the back of the tramp fairly loose (so that it hangs about 8" above the water level) and this is my boarding platform when swimming. I've tried ladders, but they are hopeless compared to rolling straight onto the back tramp. Even though the tramp is not tight, I can still walk around on it. I can't think of why you would need to go to all of that bother unless you need some structure to attach something to?

[Jay Bennett]

Hi Ian, here's a couple of photos showing the U bolts and the mooring line we use. 

[Ian Bamsey]

Thanks Roger for your input. It's tricky to make these design decisions without real experience. I'm thinking more about a rope now.

One problem I have is finding a good material in the UK. The best I can find is here. Your tramp is more a net that will deform in both directions. I'm concerned that with the mesh I have available, it will fold when stepped on. 

If anyone knows better sources of material, let me know.

(Thanks Jay for the pictures)

[Robert Hughes]

Ian, there was a thread about sources of netting a while ago - here's a link :-

http://wharrambuilders.ning.com/forum/topics/sources-for-netting?co...

I used netting from Allplas, the same as Rory.  When it was tensioned it was ok to walk on, but it tends to stretch a bit over time so you need to allow room to re-tension it later.

Here's a link to the stuff I used :-  http://www.allplas.co.uk/acatalog/45mm_5mm_Knotless_Netting.html

[kim whitmyre]

The knotless (woven) dyneema netting on Vaea is great. Somewhat pricy per pound, but you only need a bit. Incredibly strong and long lasting.