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PostPosted: Wed Jun 04, 2014 6:30 pm 
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I am planning to add a second mast base to my Oasis to turn it into a schooner.

I have considered various ways of setting up the mast base and am settling upon on the following approach subject to one outstanding modification that I will need to make to the boat.

The way a factory-fitted Hobie mast receiver appears to work is that the bottom end of the mast receiver is recessed and fits over a 'nub' that is moulded into the bottom of the boat at the appropriate point so that when the mast receiver is vertical, the bottom end is held in place by the nub, while the top end sits firmly in and is held by, the hole in the deck.

I have bought a mast receiver from Hobie as a spare part; this will drop into a hole that I will drill in the deck of the boat forward of the front hatch on my (new model) Oasis.

The mast receiver is not long enough to reach the bottom of the boat at this point in the hull so I will push & fix the mast receiver into a piece of rigid tubing long enough to reach the bottom of the boat.

All I will then need to do is create a similar nub on the floor of the hull directly under the mast base to recreate the factory-installed arrangement.

I can easily drill the required hole in the deck but what I still need to sort out the best way of adding the required nub on the inside floor of the hull. I am guessing plastic welding would be the most robust way but I am also wondering if either of the polyethylene-compatible epoxies (actually acrylics I believe) would be a viable alternative as glueing a nub in place could be a quicker, easier and less-intrusive way of achieving the same outcome.

Can anyone advise me about the likely strength/longevity of bond of one or both of the above-mentioned adhesives in the context of glueing a "nub" with a fairly small footprint to the hull in an environment where there will undoubtedly be some bilge water slopping about and the bond will be subject to some inevitable hull deformation and the shear stresses imposed by the load of the sail, through the mast/mastbase, to the nub glued to the hull? (I should mention that I can, of course create a nub with a much greater bonding surface and, along these lines, I have in my possession a section cut out of the floor of an Adventure hull with the required nub on it that I could in theory glue inside my Oasis if the hull profiles match up sufficiently)

Also, any thoughts on the advisability of this approach over e.g. plastic welding gratefully received 8)


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PostPosted: Sat Jun 07, 2014 12:36 am 
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Stobbo,
Before you go drilling any holes have you considered mounting the mast tube on the forward footwell wall?
Image
When I looked at the new Oasis when it first came out I thought how simple it would be to mount it there using blocks and saddles or maybe even stauff clamps, see
http://www.stauff.com/index.php?id=1956.
Having access through the hatch makes it easy to throughbolt and add reinforcing. It is also in a similar position to the rear sail, sitting just in front of the miragedrive for easy reach.


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PostPosted: Sat Jun 07, 2014 1:39 am 
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Stringy,

Good suggestion and yes I have. The reasons I have not pursued this approach are two:

1. Aesthetically having a through-deck installation will be much neater but more importantly,

2. While the configuration of the boat does make it very easy to install on that front cockpit bulkhead, I think that the pedals will hit the mastbase if we place it here,especially if the front occupant has long legs (like me). I have worked out by eye that the pedals will probably only just touch the mastbase if the mast base is installed parallel to the bulkhead but this will mean that the mast will not be parallel to the other mast and the overall visual effect will be very odd when the boat has both masts up. So IMO the mastbase will have to be angled out from the bulkhead at the top so that both masts stand parallel and this will mean that the mastbase will be even closer to the pedals at their furthest extension. If we add the extra girth of a couple of fittings around the mast this will only serve to exacerbate the problem.

So while it might be easier I think a different approach is called for.

BTW I have now got my hands on a plastic welder and I am going to have a go at adding a nub on the hull floor tomorrow.


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PostPosted: Sat Jun 07, 2014 2:05 am 
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Gotcha.
How are you intending to attach the mast tube to the bow deck?
Good luck with the welding and make sure you post some pics when you can. I'm keen to see how it all turns out. :)


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PostPosted: Sun Jun 08, 2014 2:35 am 
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Hmm. Well after your questionning I have had a bit of a rethink about this and maybe I will mount the mast on the cockpit bulkhead after all!

I did a bit of thinking and realised that I don't need to use the plastic mast tube if I mount the mast outside of the hull (doohhhh). I could achieve this by using an 'eyebolt and cup' system: the cup supports the end of the mast low down in the cockpit and the ring of the eyebolt supports it higher up. Of course you need to have cup and eyebolt correctly sized so that the mast will slip in easily withough slopping about but given the right dimensions that would be all you'd need and you'd probably get pretty easy rotation for roller reefing too!

So I took a trip to my local chandlery and identified a set of components that would seem to fit the mast perfectly. I then went to have another closer look at the kayak to see what the likelihood of the pedal hitting the mast and/or the fittings would be. If I mount the eyebolt high enough up the bulkhead there will be no contact between pedal and mast or pedal and fittings.

So now all I need to do is find a suitable way of strengthening the bulkhead to support the fittings and that means a thick piece of 20x30cm marine ply board cut to shape and screwed in place on the inside of the bulkhead. Then a couple of holes for the fittings and I should be good to go.

This is a work in progress...


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PostPosted: Sun Jun 08, 2014 4:51 am 
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The eyebolt and cup idea sounds good and will look better than the mast tube and saddles. The bulkhead should be a much simpler installation. Poly cutting board also works well for reinforcing and won't rot.


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PostPosted: Tue Jun 10, 2014 8:26 am 
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Stobbo, I was doing some google image searches of "schooner" and I am very interested in how this turns out for you!
Is the forward mast going to sit as tall or lower that the rear mast?
Also are you going to add amas or stick with a ballast tube to keep the kayak upright when both sails fill and try to flip you? :-)


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PostPosted: Tue Jun 10, 2014 10:49 pm 
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Both sails will be stock standard Hobie mast&sail so basically they will be pretty much the same height.

Amas are for chickens :lol:

(Actually, to qualify that last statement based on one trip in my friend's Oasis schooner: two up there is a considerable amount of ballast in the boat anyway and, subject to the normal rules of not going out in a real blow in a sail-powered Hobie kayak, there's plenty enough ballast to give a good combination of stability and sailing performance without needing to worry too much. Solo it would be quite a different story... but I still intend to find out how that story ends...)


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PostPosted: Wed Jun 11, 2014 7:28 am 
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stobbo wrote:
Amas are for chickens :lol:

blah :P
stobbo wrote:
(Actually, to qualify that last statement based on one trip in my friend's Oasis schooner: two up there is a considerable amount of ballast in the boat anyway and, subject to the normal rules of not going out in a real blow in a sail-powered Hobie kayak, there's plenty enough ballast to give a good combination of stability and sailing performance without needing to worry too much. Solo it would be quite a different story... but I still intend to find out how that story ends...)

Good point, two people on board would be enough ballast under normal sailing conditions.


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