IOM Do It Yourself DESIGN - Page 5 - RC Groups
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Nov 12, 2013, 04:14 AM
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FWAL's Avatar
Quote:
Originally Posted by Glidergirl
BTW, not surprised your club mates are upset - the place I'm sailing, there are hulls that cost c. 1,500. Mind you, the Phantom has now gone up, it's now - 71 + shipping from the UK warehouse
+1 Even the comparably cheap second hand IOM's are fairly expensive to someone who may only be interested in Club racing occasionally. Just recently older IOM's and I do mean old IOM's have been getting a very good price on E-bay here in the UK.
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Nov 12, 2013, 04:54 AM
Registered User
Don't forget my bulb is only 2200 + fin 120 = 2320. I need to get 180g on the bulb. A different battery could save 100-120. So it could be possible to get the weights right. Hull is a bit 250 - 300 over IOM so I don't see corrector weights being possible. As for the rules I think It could be possible. Where we sail we are not watching the last few grams. Failing eyesight, medication, poor concentration, shaking hands, fat fingers all contribute to going too far at the bouys. So what's a few grams between OLD friends.
I'd love to see some good IOM builder put one together just for a laugh.
Ernie
Nov 12, 2013, 01:44 PM
NORTHLAND NEW ZEALAND
D design's Avatar
There must be a maximum of 60 mm from the waterline to the keel
Nov 12, 2013, 07:27 PM
Registered User
Quote:
Originally Posted by D design
There must be a maximum of 60 mm from the waterline to the keel
I'm a bit unsure what you mean by this measurement. Do you mean rocker, the lowest part of the hull below the waterline or is it something else?
I put a straight edge on the fin where it joins the lowest part of the hull. Measuring up to the waterline I get 70mm at bow and stern. That would be over the maximum of 60mm if I've understood correctly. As I understand this would give more bouyancy in the middle and make the Phantom easier to turn. Are we talking low Prismatic Coefficient?
Please explain further.
Ernie
Nov 12, 2013, 07:40 PM
Registered User
If the hull of the boat draws more than 60mm it is not a legal IOM. Yours measures 70 so it would seem to be not legal for IOM, BUT what really matters is how it measures when the boat is floating. You need a test tank to see that. Most boats float with the bow and/or stern out of the water. This makes them draw a little less. Just to give yourself an idea of where you stand float the boat in calm water and see where the real waterline is. If the bow and/or stern are out of the water you might be OK but to be sure you have to find someone with a test tank. Or if you're not going to enter any Regattas don't worry about it. I hope you understand my babbling.
Don
Nov 12, 2013, 07:59 PM
Registered User
From the class rules:

C.4 BOAT
C.4.1 DIMENSIONS
With the boat floating in fresh water:
minimum maximum
Draught .................................................. ........................... 370 mm ..... 420 mm
The depth of hull from waterline .................................................. . ........ 60 mm
Hull length .................................................. ................................... .... 1000 mm
Nov 13, 2013, 02:59 AM
Flying without a licence
FWAL's Avatar
What is the smallest diameter deck aperture a RMG winch will fit through? I've been investigating pots and just wondering which is the best suited circular minimum size.
Thanks
Mk
Nov 13, 2013, 05:18 AM
Registered User
Thanks guys for the clarification. Crystal clear now. I took the waterline into account 70mm it is.
What advantage does increased draught give assuming bulb is at max depth?
Ernie
Nov 13, 2013, 05:50 AM
Love RC Yachts!!!
All things being equal, the deeper draft supporting 4kg, allows a narrower beam, and allows any corrector weight to be carried lower, lowering the c of g of the boat.

You'd have to add volume to the ends of the boat to displace more water, and be the boat to float higher, too hard.

In the end, despite the slightly extra draft, your speed against your local fleet is a real credit to you, with homemade sails and all. Probably make the others feel rather inadequate, hence their reluctance to talk!!!!!
Nov 13, 2013, 10:50 AM
Registered User
Quote:
Originally Posted by bigpat
All things being equal, the deeper draft supporting 4kg, allows a narrower beam, and allows any corrector weight to be carried lower, lowering the c of g of the boat.

You'd have to add volume to the ends of the boat to displace more water, and be the boat to float higher, too hard.

In the end, despite the slightly extra draft, your speed against your local fleet is a real credit to you, with homemade sails and all. Probably make the others feel rather inadequate, hence their reluctance to talk!!!!!
It's only banter. If I make quick alterations on deck it often involves duck tape. David our group organiser prepares his boats beautifully. I tell him the tape is my new graphics. I have a Shumbo ocean racer with IOM A rig. It's pretty quick too.
Ernie
Last edited by erniefoster; Nov 14, 2013 at 01:33 AM.
Nov 13, 2013, 11:15 AM
Registered User
Quote:
Originally Posted by bigpat
All things being equal, the deeper draft supporting 4kg, allows a narrower beam, and allows any corrector weight to be carried lower, lowering the c of g of the boat.

You'd have to add volume to the ends of the boat to displace more water, and be the boat to float higher, too hard.

In the end, despite the slightly extra draft, your speed against your local fleet is a real credit to you, with homemade sails and all. Probably make the others feel rather inadequate, hence their reluctance to talk!!!!!
It's only banter. If I make quick alterations on deck it often involves duck tape. David our group organiser prepares his boats beautifully. I tell him the tape is my new graphics. I have a
Shumbo ocean racer with IOM A rig. It's pretty quick too.
Ernie
Last edited by erniefoster; Nov 14, 2013 at 01:28 AM.
Nov 14, 2013, 08:32 AM
Flying without a licence
FWAL's Avatar
Sketches:
Rebated chine to help reduce leeway and perhaps provide a little lift! Think of a plane wing with a flat under surface in this case caused by the rebate. The wetted area of the hull provides the top cambered shape. Would this produce any noticeable lift?
Hinged foredeck! using a mast ram bolt to secure the desired height and a mast post to take up the side way forces exerted by the jib sheet. The idea is to keep the jib boom as close as possible to the fore deck. However, in order to do this there must be an allowance to alter the mast rake without the jib boom fouling the deck. Hence the hinge. Looks a bit complicated and the poor scanning and my drawing doesn't help but these ideas might be noticeable on my current build.
Last edited by FWAL; Nov 14, 2013 at 08:40 AM.
Nov 14, 2013, 09:09 AM
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A.B.'s Avatar
I like the hinged foredeck idea. I have thought about adding a piece of thinker mono film from the centre line of the aft deck up to the underside of main boom, this would cut off the gap between boom and deck, thus incressing sail area? right? would this be legal on an IOM?
Nov 14, 2013, 10:37 AM
Flying without a licence
FWAL's Avatar
Quote:
Originally Posted by A.B.
I like the hinged foredeck idea. I have thought about adding a piece of thinker mono film from the centre line of the aft deck up to the underside of main boom, this would cut off the gap between boom and deck, thus incressing sail area? right? would this be legal on an IOM?
As long as you can't control the shape or position whilst on the water, was made from legal substances and didn't overhang the transom then I don't think it would be breaking an IOM rule.
Nov 15, 2013, 01:40 AM
Registered User
Edited
Last edited by Tractors R Us; Nov 27, 2013 at 03:17 AM. Reason: Edited


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