trimaran plans
10-09-2010, 01:54 PM
#126
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Location: Dublin, IRELAND
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RE: trimaran plans
quick question : I see from these pics that there is no strut in front of the mast to counteract the kicker and keeping the mast straight.
On my Tri (not a Ernst design but a 20 year old French design Cobra) the mast is deck stepped and on my first sea trial after rebuilding it I couldn't control the leech of the main. It was too open and I was loosing too much power in it. So to close the leech I tighten the kicker but all it did is bent the mast as the pressure was pulling the leech tighter. The solution is to put a strut in front of the mast to the deck to keep the mast straighter.
So how do you keep the mast relatively straight and have an effective control of the leech of the main through the kicker without bending the mast ? is it because the mast is in a mast well or is it that you're using a really stiff mast section ?
cheers,
Gilbert
On my Tri (not a Ernst design but a 20 year old French design Cobra) the mast is deck stepped and on my first sea trial after rebuilding it I couldn't control the leech of the main. It was too open and I was loosing too much power in it. So to close the leech I tighten the kicker but all it did is bent the mast as the pressure was pulling the leech tighter. The solution is to put a strut in front of the mast to the deck to keep the mast straighter.
So how do you keep the mast relatively straight and have an effective control of the leech of the main through the kicker without bending the mast ? is it because the mast is in a mast well or is it that you're using a really stiff mast section ?
cheers,
Gilbert
10-10-2010, 05:53 AM
#127
Senior Member
RE: trimaran plans
ORIGINAL: GLX
Fantastic Trimaran designed by Ernst & built by Phanchita. Looks well balanced on one float and with plenty of power. The arms seems quite stiff as the platform is not twisting when on one float. Just a fantastic design and well built.
Fantastic Trimaran designed by Ernst & built by Phanchita. Looks well balanced on one float and with plenty of power. The arms seems quite stiff as the platform is not twisting when on one float. Just a fantastic design and well built.
Thank you very much.
Phanchita really did a very good job!
The arms/crossmembers need additional reinforcements, as this boat is even MORE powerful than I expected myself.
The arms are Phanchitas own design and construction.
I hadn´t discussed that with him before.
I´m still fighting with myself to continue the build of my own "Nightmare Mk.IX", incorporating my own ideas of crossmember construction, which is/will be quite different.
Idealist
10-10-2010, 05:59 AM
#128
Senior Member
RE: trimaran plans
ORIGINAL: GLX
quick question : I see from these pics that there is no strut in front of the mast to counteract the kicker and keeping the mast straight.
On my Tri (not a Ernst design but a 20 year old French design Cobra) the mast is deck stepped and on my first sea trial after rebuilding it I couldn't control the leech of the main. It was too open and I was loosing too much power in it. So to close the leech I tighten the kicker but all it did is bent the mast as the pressure was pulling the leech tighter. The solution is to put a strut in front of the mast to the deck to keep the mast straighter.
So how do you keep the mast relatively straight and have an effective control of the leech of the main through the kicker without bending the mast ? is it because the mast is in a mast well or is it that you're using a really stiff mast section ?
cheers,
Gilbert
quick question : I see from these pics that there is no strut in front of the mast to counteract the kicker and keeping the mast straight.
On my Tri (not a Ernst design but a 20 year old French design Cobra) the mast is deck stepped and on my first sea trial after rebuilding it I couldn't control the leech of the main. It was too open and I was loosing too much power in it. So to close the leech I tighten the kicker but all it did is bent the mast as the pressure was pulling the leech tighter. The solution is to put a strut in front of the mast to the deck to keep the mast straighter.
So how do you keep the mast relatively straight and have an effective control of the leech of the main through the kicker without bending the mast ? is it because the mast is in a mast well or is it that you're using a really stiff mast section ?
cheers,
Gilbert
Makes sense to me.
But depending on the mast profile/section a kicker + strut still could be necessary.
Especially for a fathead main like Ian has this will be necessary to keep the twist under control. Otherwise the mast profile would/could become too heavy, to be stiff enough.
On my earlier designs all my masts where deckstepped,
but on a new boat I would do it as mentioned above.
Idealist
10-10-2010, 06:51 PM
#129
Join Date: Jul 2009
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RE: trimaran plans
Thank you Ernst for your response. My mast is a carbon fibre diam 10mm which could be a bit on the light side. Don't have much choice on this Cobra design and I'm looking to put a strut in hope to fix this issue and enable me control the main leech. But I like the idea of a mast well as you describe. I understand the concept of a mast well but why the ball bearingat desk level ? Does the mast rotate ? On my previous IOM I had a mast well too but no ball bearing.
The big problem with this cobra design is that it was based on the successful 60 foot trimaran of the time but the weight distribution is completely different from the full size trimaran. It looks great ashore but once on the water when hit with a gust the bows tend to dig in as there isn't enough volume forward. So in my rebuilt I changed the weight distribution to put as much as I could towards the back of the main hull.
I'm alone here doing multi but I don't care I still enjoy it so much when I get to put my tri on the water.
The big problem with this cobra design is that it was based on the successful 60 foot trimaran of the time but the weight distribution is completely different from the full size trimaran. It looks great ashore but once on the water when hit with a gust the bows tend to dig in as there isn't enough volume forward. So in my rebuilt I changed the weight distribution to put as much as I could towards the back of the main hull.
I'm alone here doing multi but I don't care I still enjoy it so much when I get to put my tri on the water.
