fitting a hoop

[Nessa]

I have a hoop froma merlin rocket (ebay) which I am considering fitting to my olde kestrel. I don't have a clue how to anchor it though. Any suggestions? Everything is grp apart from a wooden thwart.

[JimC]

Its a hell of a job because it needs to be unbelievably strong due to people falling on it...
Where does it need to be in relation to the Thwart,and is the thwart really strongly anchored? I suspect big solid carbon brackets glued to the floor to anchor the hoop ends, and then another bracket bolted to the back of the thwart.

[Mark Jones]

Agree with Jim not easy to do, due to the loads involved, not even sure that it would work that well. Am trying to remember what Steve had on cmix 909 as this was probably one of the best set up Kestrel's in the 80s although already an old boat(nitronic rod rigging, slot in rudder blade and other mods) he was a boat builder!

Cheers
Mark

[jpa_wfsc]

Hoops are only really useful if you have a powerful, stiff kicker.

And that also leads to a need for stiff lower mast (mast gate ram or lowers).. which needs a stiff deck, which needs a stiff hull...

and so on....

I suspect that even a Kestral (heavily built in GRP) will simply not be stiff enough to gain any advantage. All you will do is add weight for no particular gain. I would instead explore split tail boom end sheeting with the sheet led along the boom to the centre position. Most Albacores use this now. With the split tail method you can get centre-position sheeting without appreciable downward pull on the boom to get good rig for light wind, and which is what hoop systems are aiming to do.

Hoops are also a megga pain for roll tacking - and that's something a Kestral needs to be good at.

[Nigel]

Tempting to think of them as a sailing variant of a zimmer frame . Something for those of us with dodgy joints etc. to grab hold of to help with mobility.

[Nessa]

I am considering the split tail option - we used these a lot in 470s so I know the pros and cons - but I also think the hoop would suit the kestrel and many seem to have it fitted. I've used it lots on fireballs and the like and it worked well. If it's going to be a pain to do I shall simply go for either split tail or a basic strop, or a combo of the two. It's become worth tarting up the old bird since she is about to receive a new mast, courtesy of the Hunts cvrda wipe out.

[alan williams]

Hi Nessa
I like hoops and the fastest Hornet that I owned was fitted with one. Loads are relatively high but the Kestrel in Sailing School Spec. which I believe is the type you have is a strong beast. I would lock it into the thwart and then build two sockets which could be directly bonded to the hull using suitable load spreaders. You would need a decent cascade kicker to gain any advantage though. Used to find the hoop very useful when roll tacking as it can act as a handle to really pull the boat over and back up, timing is the thing to get right.
Cheers Al

[Nessa]

I did have the thought about using the thwart, it's bonding to the floor which I'm not sure about. The boat is home for a strip down and repaint etc plus the refit the new mast will necessitate.

If the hoop acts as a zimmer frame then I'm all for that, plus I'm looking forward to the space after crawling around in the moth!

[JimC]

I did have the thought about using the thwart, it's bonding to the floor which I'm not sure about.

You want both I think as I suggested. The ultimate mechanical solution, I suppose, is through bolting through the floor with countersunk bolts on the outside, but I dunno, I'm never really happy with that even though I've done it when no better solution was available (kicker anchorage on floor of harrier).

What I would do is to make up a couple of L shaped or T shaped brackets in carbon fibre, probably about 4 inches long by two inches wide and deep. I suppose you could use glass if you wanted provided you can get some really good quality glass, preferably a bi-axial cloth or something, not chopped strand mat. Make a little jig for them to get the layup really consolidated. All this needs is a piece of 4*4 timber about a foot long, and two pieces of 4*1 about the same length. You cover the 4*4 in parcel tape, and then glue the two bits of 4*1 into an L section, using the 4*4 as a mould. Cover the L section in parcel tape when you've finished. Then you lay up your carbon cloth on the 4*4 across one of the corners, with peel ply down first unless you insist on a shiny surface. As many as possible of the fibres cross the 90 degree corner at different angles, lots of them should be 45 degrees as well as straight across. Then put th L section on top of the laminate and clamp down with G cramps, pretty much as tight as you like. Excess resin will all squeeze out. When cured unclamp, knock the jig apart, remove the bracket, cut into two/four and you have your brackets. Two L shaped back to back = one T shape.
To attach the brackets to the boat without mechanical fasteners first clean up decent area (6 inches square?) with acetone/abrasives/everything you can so you are down to the initial layer of fibres. Depending on how much curve there is in the hull start by putting on layers of glass of different sizes to make a flat area. Piece of wood with parcel tape pretty good for getting flat. Important to use eel ply on each curing session to ensure good bonding for subsequent layers.
Then glue down your brackets in position in the middle of the pads. When cured use a good strong filler round the pads to bridge the width of the pads and make a continuous plane with the rest of the surface.
Finally several layers more of cloth over both bracket and pad to lock it in position. These should not all be the same size: you want maximum strength next to the bracket but with the glass feathering out to one layer at the edge of the prepared area.
Do this well and you'll have a pair of brackets on the floor you could lift the boat with...In fact I'd want to be confident I could do exactly that for the required strength.

[Nessa]

Yikes. The split tail and strop is suddenly very attractive. Thanks for the description Jim, but I know my limits and that might be beyond me.

[JimC]

Yikes. The split tail and strop is suddenly very attractive. Thanks for the description Jim, but I know my limits and that might be beyond me.

Not as bad as it sounds actually. Try making up the brackets if you have material to hand and see how you like the results. Then you can either throw them away or continue as the resulting confidence factor dictates.

[Rupert]

It is possible to put it in using blocks of wood on the floor, too, with holes drilled to take the hoop, which might appeal more? Strongest way to fit them is to screw right through the hull up into the blocks.

[Pat]

On the Merlin the hoop supports are built into the centreboard case and then it's secured at the bottom. I've emailed you a picture as the board attachment quota has been reached so I can't post it.
The Lark just has a bridle to raise the first block closer to the boom and the Albacore has a split tail main and that works fine although you don't have the multiple purchase of a hoop or bridle system.