Trim Angle?

[PaulP]

I am trying to get info on trim angle. Don't want to be a stick in the mud but just about ready to say "take your discussion about A boats somewhere else. This is for EC12s

[V][:D]

Paul P

ps: and I still am soliciting discussion on the trim angle

[Larry Ludwig]

OK,

I would be intererested to learn how to accurately measure within .10 of a degree of the angle.

Thanks

[PaulP]

Larry,
In the EC12 Optimizing (Book 2), Larry illustrates his tool for measuring trim angle. I have built one and it is surprising accurate.

The problem I run into is measuring the waterline. It is extremely difficult to gauge front and rear at the same time. It really is a two man job.

Do you have the Book 2? Have you tried the trim gauge?

Paul P

[kahle67]

Paul, no nautical engineering degrees here, just trial and error. But if you want to know where I am, here it is.

Given that the deck is a straight line from bow to stern down the centerline, I measure from from here. When I say "measure" I am speaking of a level gauge with the bubble, not an accurate tool. Also consider that I have a relatively short pour at 13.5" which makes it easy to change the angle by shifting your trim weights around.

When the conditions are light, I am dead level at a 42" waterline. In this mode, the boat is at its lightest displacement with all of the weight in the middle of the boat. Tacks are easy and accelleration is good. In medium light conditions on up, trim weight is placed right behind the permanent ballast and when I get past the 42.5" waterline and approaching 43", the bow comes up about a degree. In a Regatta with a consistent heavy blow, I ride with long trim weights that are the length of the bilge (7") long. This brings the bow up to about 2 degrees. Once again, these are not measurements, just guestimates.


1767

[Larry Ludwig]

Paul,

I don't have any of the books, I am a dinosaur when it comes to such things.

I use a laser level and a plumbed 10' spar dry mounted (not permanently obviously) into the open hull <u>without </u>the deck in the test tank.

The laser is reflected in all 4 cardinal directions and each aimed on its own target so if/when something moves I know it. 2" of travel on the lazer dot is worth about 1 degree. John Reynolds created a nice set of templates for waterlines that fit inside the open hull, and after putting my PC on the numbers and having them re-checked over at SouthWest Research I have learned that I could have saved myself a lot of time since `ol John had it pretty much figured out a long time ago.

[s vernon]

Larry,

Here is something for you... Oh sorry, it only measures within 1/8 of a degree not 1/10.

http://www2.towerhobbies.com/cgi-bin/wt ... LXET66&P=7

It stands there nicely on the deck while you read it.


Scott

[MichaelJ2K]

Paul,
It looks like I failed to emphasize the point that trim angle could be determined by measuring along a theoretical water line at three points, fore, mid and aft. I wanted to use the A boat as a reference as to how it was done. Sorry for the confusion.

Mike


<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by PaulP</i>

I am trying to get info on trim angle. Don't want to be a stick in the mud but just about ready to say "take your discussion about A boats somewhere else. This is for EC12s

[V][:D]

Paul P

ps: and I still am soliciting discussion on the trim angle
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

[Rick West]

Guys,
Reichard makes a good notation regarding the deck that may have been missed in my long statement on the other page. The trim angle is measured on the deck and with a tool just as it was in the Manuals, see this photo. http://www.ec12.info/Final%20Weigh-In.htm If built correctly, the crown of the deck is a straight line between the center top of the transom to the tip of the bow. This is the reference point for the trim angle. Without more sophisticated tools, this is the best and most convenient place to do calibrate from.

What the angle is to the waterline (measured length) is only a relation to the weight of the boat for the conditions you are sailing in. It has been found that the lighter the air, the lighter the boat and a lesser positive angle to the bow is best and visa versa.

The waterline of the boat is a measured length reported in a tank by the amount of ballast that is installed. When ballast is installed, or removed, (behind the primary ballast) the boat will float as it will from the building and the deck line will be what it will be.

A trim weight is introduced to create the angles you want (deck to the level water of the tank, like in planet) for the various weights you will select from. This is usually four.

To be technical, if you change the angle of the trim, it will change the waterline length to an nth degree because of the curves to the bow section and at the stern. Hence, you seek the trim you want and then check the waterlines at light ballast and heavy ballast to see if you are within the required 42-43" restriction.

When we are talking waterline in the EC12 it is that of a rule. When we are talking trim angles it is that which the EC12 has been found to best move through the water at various conditions. To me that is what is meant by sailing on her lines. To me there is no technical or designed line on this hull that represents "Her Lines."

When Bill and I approached the problem for the first time having not a clue what we were doing, this was the concept we perceived from the Optimizing Manual and applied it with common sense. This was documented in <b>The Weight</b> section of the <b>Electronic Checklist</b> and the two pages under that heading. To this date nothing has presented a reason to move from that concept. We have ignore the technical because we could not quantify it and so it became a living thing.

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