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post #1 of 14 Old 12-06-2013 Thread Starter
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Sailboat performance change

Hi All - I drive a CAL 39 MkII that I've owned for 18 months. Just starting to fix 'er up for cruising. The dodger that came with the boat is fairly small. The boom just passes over the dodger and limits my visibility ahead unless I stand on some seat cushions to get my line of sight above the dodger.

I've figure I could have a lot more visibility if the windshield of the dodger was more vertical and the height of the dodger overhead was raised. One alternative I've thought of is to raise the boom 5-6in. and have the main sail shortened that much from the foot. Is there going to be a very dramatic shift if seaworthiness and/or handling?

Thanks in advance for the knowledge and experience you share with me.

Last edited by windketch48; 12-06-2013 at 06:11 PM. Reason: wanted to add a "thanks in advance
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post #2 of 14 Old 12-06-2013
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Re: Sailboat performance change

Vertical dodger windows rarely 'look' right.. and you need to be a little careful with dodger height - another 'visual' that needs to be the best compromise between utility and appearance. Because we had a large, high bridge deck we spent a lot of time mocking up ideas until we came up with what would work and not look silly. A large radius dodger frame is one way (as opposed to 'hard shouldered' square-ish frames) to get more ability to 'look around' it and a higher center 'look through' area.

As to modifying the main I'd be tempted to leave the tack alone and just have the clew raised as much as you need, minimizing the loss of sail area and simplifying the modifications. That may involve relocating the vang connection if it's a rigid vang, but otherwise it's just a sail recut rather than moving the gooseneck.

Ron

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".. there is much you could do at sea with common sense.. and very little you could do without it.."
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post #3 of 14 Old 12-06-2013
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Re: Sailboat performance change

Moving the boom will likely be expensive, since it means re-cutting the mainsail and possibly adjusting the sheeting system to accommodate the changes too. You might be able to get away with leaving the gooseneck in place, and simply angling the boom up at the aft end. That could look really screwy, though, It might be cheaper to simply make the dodger shorter, so as to open up a slot you can see through between it and the boom. Changing your height of eye with a raised grate (instead of seat cushions) might be even cheaper. Raising the boom just a few inches probably won't have a huge effect on handling, but it could make the boat look a bit funky or topheavy. I'd sail with it a bit longer and think about all the options before I made major changes. It's been OK for twenty or more years... what's the rush?
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post #4 of 14 Old 12-08-2013
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Re: Sailboat performance change

A photo of your existing dodger and cockpit would be very helpful. Dodgers rarely limit view of the sail from the cockpit, do you also have a bimini?

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post #5 of 14 Old 12-08-2013 Thread Starter
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Re: Sailboat performance change

Hi Again...

Yes I have a Bimini top. The forward frame is even with the vertical midline of the boom profile ands about 6in aft of the boom's end when it's centered. The view that the "low" dodger limits is not that of the sails, but the view fwd of the vessel in general. Not safe when negotiating unfamiliar water, especially channels. The thrust of my question was to raise the height of the roof of the dodger (thus making the fwd statglas window more vertical), raising the foot of the sail (and therefore the boom as well) by the same amount, estimated to be 6in. By lowering the Bimini slightly I'd be able to get a cover flap from the fwd Bimini rail to the aft dodger rail and thus close that rain gap as well. My concern has been any serious potential change in seaworthiness due to the relocation of the CE of the mainsail.

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post #6 of 14 Old 12-08-2013
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Re: Sailboat performance change

Instead of raising the dodger, consider lowering it so that you can see over it. That's the situation that we were in when we bought Victoria. Looking through a dodger is not nearly like looking through a windshield of a car, even with pristine Stratglas. So we lowered the dodger to a height that my wife could see over. The dodger is really only meant to be sat under, after all. It looks better and the angle of the forward screen is more raked, better matching the cabin top lines. Faster is right.

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post #7 of 14 Old 12-09-2013
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Re: Sailboat performance change

Bimini-Dodger combos can make it really hard to see out of the cockpit and to see sail shape. I like the shade that the bimini provides for a couple of weeks a year, but hate it most of the time. However you are in FL and they might be a fact of life there.

Are either of them designed for quick folding? In FL I'd think that you'd want to be able to fold the dodger down quickly so that you could get a breeze through the cockpit anyway. On some dodger designs this is as simple as unhooking two straps (one on each side) and pushing it forward against the cabin top, it really only takes a few seconds.

If that is the case you could just fold the dodger down before docking.

Otherwise I agree with others that the best plan is to lower the dodger, not raise it.

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post #8 of 14 Old 12-09-2013
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Re: Sailboat performance change

If understand it correctly, the head sail gives you power and the main gives you heal (and weather helm adjustment). So IMO you would see little dropped performance issue. Did I miss you saying if you are racing or cruising? Sound like you are a cruiser, having a dodger and if performance was a real issue with you would take it down. And, I am surprised no one has mentioned the air stream of the rack of the windshield, more vertical will act more like a sail! That can be bad and good...I can do 2k down wind with no sails up. On my old boat I have a track, 12" long, to adjust the height of the boom. There was a thread a short time ago about the usefulness of this track and as others have done and I did a long time ago was to tack the car from moving. Mine in the all the way up position, my boom just clears my dodger. I am not racing, but would think the lower the center of gravity the better, but not sure if that apply s to the main.

Edit: If you raise your main 6" and shorten the sail you will only be changing the center of gravity 3"

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Last edited by Delta-T; 12-09-2013 at 10:57 AM.
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post #9 of 14 Old 12-09-2013
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Re: Sailboat performance change

Simple math tells the OP's original line - you will loose about 7 sq ft of main sail.
You will loose it at the bottom where the wind is slowest, you will loose it along the boom where the wind is squirrely anyway.

On the other hand, it will be expensive, more so than lowering the dodger and making a window in the connector between the dodger and the bimini.
I don't have a good pic of ours - here you can see the tan colored phifertex covering the isenglass, and the dark blue in the center is a removable cover as well. The phifertex is 80%, you can see through it for most purposes, but not enough to be safe underway, it comes off for full visibility, and a full blue cover goes on for sitting at the dock most times.

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post #10 of 14 Old 12-09-2013
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Re: Sailboat performance change

Quote:
Originally Posted by chucklesR View Post

On the other hand....
I was just going to do that....lol

On the other hand, The bigger the dodger the more resistance. And I hate looking through the dodger anytime. I would prefer to have no dodger, but hope to have waves braking over the bow every time I go out. Go ahead and call me a cruising *****, I good with that. I don't own a racing boat. But I will give you a run for your money with against cruiser. My vote is for smaller dodger, but the question was if performance would be compromised. And at what wind speed, after 17k apparent (give or take), you will have more sail than you need.

Edit...hahaha I was censored "*****"

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