IOM Building Question #1 - Ballast Bulb

Two weeks ago I asked via this board for advice on how to fit out and finish the assembly of my IOM “Kite”. Being a first time IOM owner, I’m hoping to do it up right and with the advice of IOM experts. Feedback messages indicated that I would get all sorts of free advice. This is good.

My reason for not getting back right away with my IOM building questions is because I ventured away from home in Chicago so as to particpate in the 2004 M Class National Championship held this last weekend in Port St. Lucie, Florida. Note that I said “participate” and please just leave it as that – No one is to ask how I “did”!

On second thought, I’ll let you figure out “how I did”. My non-updated, nine year old M with nine year old sails could be launched by wading out up to my knees rather than be launched by wading out to my waist like everybody else down there. Also, my boat was not made in Germany and not black in color. I was, however, first to round the first mark in the first race – Very encouraging! By the time I made it to the second mark, I was dead last – Very humbling!

While there for the M event I had the pleasure of meeting in person two guys who really know IOM and who are likely to go on record as the two top salesmen for the IOM Class, Tony Gonsalves and Peter Allen. Tony is the current IOM US champ. Peter is the current runner-up IOM US champ. My making mention that I’m starting to put together an IOM started Tony and Pete telling me how much I’m going to like the IOM. You would need to have been there to appreciate their enthusiasm for the class.

Incidentally, Peter Allen was 2003 US M Class Champ. He is now, for 2004, repeat US M Class Champ. Tony Gonsalves was not able to sail this event, but he did spend a day visiting.

Hokay. 'Time for IOM Building Question #1: I need a keel bulb. I’m assuming that the right thing to do is to order the “Out of Stock” (for now) “IOM Ballast” by SAILetc. from GBMY. Once I get hands on one, where do it fit it on the keel fin? Yeah, yeah, on the bottom of the fin and lined up fore and aft! But, rather I want to know how far back from tip of bulb to leading edge of the fin might balance weight the best. Another query: Do I want the bulb parallel to what I think might be the waterline, or should I throw in a little bit of up-angle to the bulb?

rich
i put my bulbs with a little “up-angle”. we all know that the boat under power. has a litlle bit of pressure and forcing the bow into the water. what happend under water is that the fin is slightly bent back and the bulb is no longer parrell with the surface of the waterline. with the “lets say 3 degrees” of up angle. it now causes lets drag?
as to attcahing the sails ect bulb. i dont have one. but if it has a slot cut into the bulb. i would just used a slow cure epoxy. I own a epoch from climate boatworks. and i just used thier method. and i use epoxy and it glues lead and aluminum. it works real well
i hope this helps. and welcome to the fartenity. you owe us the first round at your first race
cougar

Hi Rich

Amount of “nose up” can depend on your design’s transom beam. Have a look at my Web page on the topic, at

http://www.onemetre.net/Download/Bulbcant/BulbCant.htm

In general, you’d probably want somewhere between one and two degrees.

Position of bulb – you’ll want to place it to achieve the “right” immersion of your transom. Some designs want their transom immersed 1 mm, others 3 mm, etc…

Lester Gilbert

I don’t know that much concerning the IOM class, but I have built and sailed many Marbleheads. I used to make my own bulbs. Try giving this ago. The mould can be made quite easily. I’ll explain how I use to do it if you are interested?

Is there a reason for using bulbs supplied by Sailsetc or is it just a case of “that;s what everybody uses”
Peter

<blockquote id=“quote”><font size=“1” face=“Verdana, Arial, Helvetica” id=“quote”>quote:<hr height=“1” noshade id=“quote”> Some designs want their transom immersed 1 mm, others 3 mm, etc…

Lester Gilbert
<hr height=“1” noshade id=“quote”></blockquote id=“quote”></font id=“quote”>

This caught my interest. I was under the impression that the transom should just touch the water. If a designer wants the transom a bit under water (at rest I assume) would it be because when the boat is under way it would lift the stern?

Thanks
Don
Vancouver Island

<blockquote id=“quote”><font size=“1” face=“Verdana, Arial, Helvetica” id=“quote”>quote:<hr height=“1” noshade id=“quote”>Originally posted by Don If a designer wants the transom a bit under water (at rest I assume) would it be because when the boat is under way it would lift the stern?<hr height=“1” noshade id=“quote”></blockquote id=“quote”></font id=“quote”>
Hi Don

There is a theory that, towards the top of hull speed, the “attitude” of the boat within its wave trough is “better”, making the hull wave “think” the boat is longer than it is. Well, who knows! I think a better explanation is that the boat’s distribution of weight is better to counteract nose-diving…

Lester Gilbert