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tink View Drop Down
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Post Options Post Options   Quote tink Quote  Post ReplyReply Direct Link To This Post Topic: Hardware development
    Posted: 11 Feb 22 at 7:29pm
I was once sailing my IC and noticed the mast had developed a lot of rake. I looked to the bow and the whole of the foredeck was coming away from the hull and I was sailing with what looked like a giant biting mouth. 

Got back to shore with the mast intact and all pins in place. Was on the start line next day thanks to 8 inches of 4mm stud iron, nuts, washers and some PU glue (works on wet wood and was only local available at the local undertakers) 
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getafix View Drop Down
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Post Options Post Options   Quote getafix Quote  Post ReplyReply Direct Link To This Post Posted: 01 Mar 22 at 2:35pm
Hopefully this is the right thread for this question. I couldn't work out from the search results if such a thing has been asked and answered already, or not, so here goes.

I noticed a lot of t-foil rudders at the dinghy show and these are now on craft such as N12 where I understand they benefit all those wishing to actually survive a bear-away in F4+ by stopping the nose diving and enabling the crew to even contemplate gybing in waves as well.

Systems to control the rake / angle of attack (someone feel free to correct) seem very well sorted, there very neat examples on canoes, the rainbow N12 and so on.  So, here's the questions:

i) do t-foil rudders benefit in other ways than just avoiding nose-dives? presumably lifting the back of the boat is advantageous upwind as well?  If so, how?
ii) is there a speed cut-off where they don't or won't work or be so ineffective as to not make it worth the extra hardware to implement?
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Post Options Post Options   Quote eric_c Quote  Post ReplyReply Direct Link To This Post Posted: 01 Mar 22 at 5:00pm
Originally posted by getafix

Hopefully this is the right thread for this question. I couldn't work out from the search results if such a thing has been asked and answered already, or not, so here goes.

I noticed a lot of t-foil rudders at the dinghy show and these are now on craft such as N12 where I understand they benefit all those wishing to actually survive a bear-away in F4+ by stopping the nose diving and enabling the crew to even contemplate gybing in waves as well.

Systems to control the rake / angle of attack (someone feel free to correct) seem very well sorted, there very neat examples on canoes, the rainbow N12 and so on.  So, here's the questions:

i) do t-foil rudders benefit in other ways than just avoiding nose-dives? presumably lifting the back of the boat is advantageous upwind as well?  If so, how?
ii) is there a speed cut-off where they don't or won't work or be so ineffective as to not make it worth the extra hardware to implement?

Obviously they are banned in most classes.
As regards the parameters for  T foils improving performance, I think that may depend on whether you're slapping aT foil on an existing hull, or designing a hull to work with a T foil. I think some boats switch back to a normal rudder for light airs?
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JimC View Drop Down
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Post Options Post Options   Quote JimC Quote  Post ReplyReply Direct Link To This Post Posted: 01 Mar 22 at 5:53pm
Originally posted by getafix

do t-foil rudders benefit in other ways than just avoiding nose-dives?

The more you lift the boat and reduce displacement the less water you are pushing out of the way, which is of course less form drag. Two sided high aspect ratio shaped foils lift the boat a great deal more efficiently than the one sided very low aspect ratio bottom of the hull.
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Gfinch View Drop Down
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Post Options Post Options   Quote Gfinch Quote  Post ReplyReply Direct Link To This Post Posted: 03 Mar 22 at 8:11pm
We haven’t found a speed ceiling yet with the T Foil.

On the N12:
1) Stability at speed
2) Transom lift
3) Pushes stern wave back, tricking the water into thinking the boat is actually longer than 12ft
4) Can adjust angle to lift the bow up in waves

In the N12, T Foils work on some of the older designs, but not so well in lighter airs, where a standard blade works better. On the Dead Cat Bounce, works well above 5kts of wind.
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