Nice photos man

Originally Posted by gpzy

Here are some pics from Race Week 2009 in San Diego. Wish I new the names of sailors and hulls.

http://www.flickr.com/photos/9383481...7621860252891/

Some pics of my (kind of )local spot.It is a two hour drive but worth the trip.
This is Tauranga in NZ.This will be the site for the 2010 IOM Nationals.
http://www.ohope.co.nz/iom/index.html

Should mention in regard to last post that entries are coming in fast and there has been talk of putting a limit on numbers for logistical reasons....so if anyone is thinking of making the trip from overseas an early entry may be the way to go....
Nats are on March 20 to 22 2010

Originally Posted by hew565

Are you saying that with a separate trim on the jib, that the nose of an IOM will not submarine in a breeze? Or that I will not need a rudder that will "boil the water"?

I do like some weather helm on my boats and feel it is faster than no-helm upwind. You will not be able to detect a lift if the boat does not want to naturally head up into it.

Are there any "real" boats that are sailing with a "laminar flow" hull that you describe? Since all "real" boats have a separate jib and main trim, why do they need rudders?

With a twice around upwind/downwind course taking about 12 minutes to complete, how much time will you lose trimming your jib instead of hitting the shifts? Will you be able to manouver with another 20 boats at the starting line with a "variable camber" rudder?

Hull design will stop the submarining, separate jib control will reduce boiling.

If you understand exponential throws it is possible to have a rudder that is variable camber around its centre but which becomes traditionally active beyond 25% throw. The variable camber will reduce induced drag when traditionally active. Yes you do need a rudder for aggressive start line positioning but until 10 seconds before the start you need placement control rather than ultimate boat speed.

If we were sailing identical boats yours trimmed for weather helm and mine not you would do trim out your weather helm in an instance. If you are at the front of the fleet sailing with weather helm then I am happy to say I am wrong and adopt the same technique. As soon as I have learnt what you are doing better than me I will go back to beating you.

After the start a rudder is along for the ride or for the aggressive change of direction. Given a choice would you rather give yourself clear air and boat speed and sail confidently across the fleet on Port or are you happy to tack into their lee and follow them for another runner up placing.

With the ability to adust the jib independantly you will not lose a single split second in your 12 minute race it is an automatic function . If you have flown manually coupled aileron an rudder on fixed wing or have "flown" the tail rotor on a helicopter you will know that very quickly it is possible to split think your fingers and thumbs on your individual hands.

I am not here to throw sticks in the IOM pond, it was pointed out that the rules are International and therefore won't get changed. RCGroups is also International and it only takes one person on one of those governing bodies to read this thread that it is possible to consider a small change to the rules to improve the class and change becomes a possibility.

I dont understand exponential throw let alone variable camber rudders.............please explain so I can get a handle on what you are saying.
Please do it in laymans terms if at all possible.
Thanks in advance,
Richard

Robert,
Don't be sorry for what you are saying I find it very interesting, I was the one who said my boat is s%@& down wind but that is because of the width of my hull, to windward i can out point nearly everything and that is how a boat that is 8 years old, a copy of a 15 year old hull and weighs between 4.2-4.5kg, can still keep up with the best and newest boats in the club (as long as i stay concentrated and watch my sails).
Please keep explaining I am intrigued and this is why I started this thread not to bag each other but to listen to different opions.

Mike
TS-2 Clone
AUS 669

Originally Posted by k4s

I dont understand exponential throw let alone variable camber rudders.............please explain so I can get a handle on what you are saying.
Please do it in laymans terms if at all possible.
Thanks in advance,
Richard

Variable Camber; have alook at what the advanced RC glider boys can do with their wings. Wings, like rudders, work by creating lift on one side of the surface which then sucks the surface towards the lift. You will find very few symetrical wing or flat plate wings on gliders because they rely on the angle of attack to create a relatively inefficient lift where you get more drag (Drag = brakes) for the same amount of lift. Instead by effectively changing the camber of their wing the glider boys aim to get more lift and less drag. (Aerobatic slope soarers don't need lift, the slope provides their lift so they do have symetrical wings) Most rudders are either flat plate or symetrical sections and rely on dirty draggy lift to change the course of the boat and they are doing it in water which is a comparitively thick fluid for 1 metre boat.

Rudders ar great for quick and coarse changes of direction but the penalty is drag, you put the brakes on. Anyone sailing with any weather helm is sailing with the handbrake on.

Exponential is fairly common in most radios these days. Instead if have a linear (equal change) of servo movement per equal movement of the transmitter stick it is possible to dial in "Expo" travel, where it is possible to move the servo only 5% of its travel when moving the stick by 25% of its travel. This gives a very accurate and delicate touch to the centre stick movements (lots less movement = lots less drag = more speed) In the heat of battle shaky fingers are dabbing in little bits of drag every time you touch the rudder stick. Every single correction adds more drag.

Originally Posted by 8387mike

Robert,
Don't be sorry for what you are saying I find it very interesting, I was the one who said my boat is s%@& down wind but that is because of the width of my hull, to windward i can out point nearly everything and that is how a boat that is 8 years old, a copy of a 15 year old hull and weighs between 4.2-4.5kg, can still keep up with the best and newest boats in the club (as long as i stay concentrated and watch my sails).
Please keep explaining I am intrigued and this is why I started this thread not to bag each other but to listen to different opions.

Mike
TS-2 Clone
AUS 669

What is wrong with the width of your hull Mike? I'll give £10 to charity if this is your hull design. Sounds like someone wants a few of your Dollars. (quite a few probably)

Is the ts2 a narrow design hull? How does she sail in light wind ?
Here are some pics of my Southern Cross-4.

A hull capable of being fast to windward normally means it fast downwind too.

Rather than sort out what that problem is and bury the discussion in this thread. That would make a fanstastic and interesting thread in its own right.

Who knows the thinking behind skiff style designs and why are they so popular? It strikes me that if IOM courses do not have reaching legs (as someone pointed out earlier in this thread) why have a planing hull form on a displacement yacht? Does anyone have photos of model yacht (any class) planing?

Originally Posted by Robert May

Does anyone have photos of model yacht (any class) planing?

Obviously not Bob - since moving ballast is also illegal in most (not all) classes. Once you hang a "blob" of lead under a hull, regardless of design it really does become a displacment hull of one level or another.

There are photos of models that "appear" to be ready to plane - or that actually may have exceeded hull speed for a moment or two - but to sustain planning over any distance/time by most models is as you post, pretty rare if indeed it happened.

I won't touch on the subject of foils in this post, nor on asy spinnakers or multihulls - all of which could lend themselves to further speculation/argument. Would leave this to strictly the IOM class. Too easy to hijack a thread with examples or speculations. Just wanted to point out there are other ideas that approach or exceed true wind speed - but to my knowledge the IOM isn't one of those designs - (right now).

Is there a IOM kit that is available for under $1000? What is out there and where to buy new?

May want to direct that question to the US class secretary - Steve Landeau.

If anyone would know, I would think he would be staying on top of any new class developments. Visit the AMYA web site and look under "classes" for a link or phone number.

Originally Posted by Dick L.

Obviously not Bob - since moving ballast is also illegal in most (not all) classes. Once you hang a "blob" of lead under a hull, regardless of design it really does become a displacment hull of one level or another.

There are photos of models that "appear" to be ready to plane - or that actually may have exceeded hull speed for a moment or two - but to sustain planning over any distance/time by most models is as you post, pretty rare if indeed it happened.

I won't touch on the subject of foils in this post, nor on asy spinnakers or multihulls - all of which could lend themselves to further speculation/argument. Would leave this to strictly the IOM class. Too easy to hijack a thread with examples or speculations. Just wanted to point out there are other ideas that approach or exceed true wind speed - but to my knowledge the IOM isn't one of those designs - (right now).

It is for exactly this reason that I simply do not the modern trend for hull forms more suited to a dinghy than a yacht. The photo of GPZY's Southern Bell is fantastic but look closely at the water and it shows how that boat is desperate for slightly wider shoulders (15mm a side directly under the no 36 on the jib) and slightly narrower hips and legs. The result would be a resist that heel and all that power would transmit backwards.

BTW I would buy a Southern Bell based on those 2 photos, I would fit a jib trimmer and have myself a very nice boat.

Dick been on other sites, but have found RC Groups to be one of the most active forums.