Keel of Adelie 16

Sail Boats 15' and up. Please include the boat type in your question.
jbro5000
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Re: Keel of Adelie 16

Post by jbro5000 » Fri May 19, 2017 10:51 am

Thanks everyone for these further helpful comments.

I researched well the market before buying the Adelie 16 plans and agree that all things considered it is a very well designed vessel and the various comments give excellent reassurance on that.

I an not doubting the design but seeking clarity on what appears or appeared to be some inconsistency in the wording of the study plan and the building notes which made me wonder at what draft the stability calculations were made

I did not measure precisely from the plan but had the impression that to arrive at a draft of 35 inches the CB would be need to be vertical and not at an angle as shown in the plans. There is a locking position for that latter position but the construction notes seem to refer to it as a 'half way position.

The plans make all good sense if the fully down position is with the CB at the angle drawn on the plans and as the CB housing is also drawn and not with vertical CB...I am just not sure yet on what was the position of the CB for the stability calculations.

Positive stability at an angle of heel of around 130 degrees is about normal for a vessel sailing offshore, far from assistance. As we know the worst sea states are usually just off exposed headlands which not offshore in the sense that regulatory bodies base their rulings.So I simply want to be sure I will get the best stability possible from the vessel

I agree with the comment that the vessel will have valuable fore and aft stability with the CB presenting a longer profile when in the water than if vertical and I would certainly not prefer to sail this vessel with the CB vertical because recovery is also much more difficult and inconvenient.
If necessary I would put more weight in the CB to avoid recourse to the vertical CB scenario,

I am still getting quotations from builders at this stage and there is plenty of time to get clarity on these finer points.

Kind regards



terrulian
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Re: Keel of Adelie 16

Post by terrulian » Fri May 19, 2017 11:04 am

I am still getting quotations from builders
Does this mean you're going to have someone else build it?
That would be unusual here so if that's what you plan, let us know how it goes.
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pee wee
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Re: Keel of Adelie 16

Post by pee wee » Fri May 19, 2017 11:30 am

jbro5000 wrote:
Fri May 19, 2017 10:51 am

Positive stability at an angle of heel of around 130 degrees is about normal for a vessel sailing offshore, far from assistance. As we know the worst sea states are usually just off exposed headlands which not offshore in the sense that regulatory bodies base their rulings.So I simply want to be sure I will get the best stability possible from the vessel
Maybe I'm not looking at it right, but I thought 90 degrees would be mast parallel to the water, and 130 degrees would be well on the way to upside down . . . and still trying to right itself.

Edit: Okay, I see what you're talking about, but not why you're worried about these numbers and this boat. A little homework turned this up:

The reason 120 degrees is considered the minimum AVS standard for most bluewater boats is quite simple. Naval architects figure that any sea state rough enough to roll a boat past 120 degrees and totally invert it will also be rough enough to right it again in no more than 2 minutes. This, it is assumed, is the longest time most people can hold their breaths while waiting for their boats to right themselves. If you don't ever want to hold your breath that long, you want to sail offshore in a boat with a higher AVS.
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Re: Keel of Adelie 16

Post by terrulian » Fri May 19, 2017 11:57 am

Here's an explanation:
http://marine.marsh-design.com/content/ ... ity-curves

Worth noting is the second diagram, paying particular attention to the "typical sailing range."

Almost everyone will reef at the top end of this range and beyond that, depending on the design, the boat will get squirrelly and hard to control if you don't. A boat gives very good feedback about what's safe. To repeat myself, I've never had the spreaders in the water (a little less than 90 degrees), or even come close. To do that, you have to be flying a spinnaker at the extreme and no one does this when they're not racing. Notice in this video (in my dear SF bay) this boat is completely overpowered in a broach and the mast still never gets lower than about 60 degrees off vertical. You're not going to do this, right? And I'm guessing the Adelie has a more conservative design anyway.
https://www.youtube.com/watch?v=8sd513xQzV4
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jbro5000
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Re: Keel of Adelie 16

Post by jbro5000 » Sun May 28, 2017 3:27 am

I have looked at the plans more carefully and it seems the indicated draft of 35" and CB 'fully down' position is with the CB at an angle as drawn on the study plans and full plans). The plan shows a locking arrangement for that position.

On that basis I have no more questions and I am convinced that the standard design is very well considered.

I am seeking quotations from experienced foam construction builders for hull and decks and will try to do the remainder of the work myself.

Kind regards and thanks again for valuable insights from the various posts.

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Re: Keel of Adelie 16

Post by terrulian » Sun May 28, 2017 9:44 am

Great. Please keep us informed. Pictures from a pro building with foam would be very interesting and appreciated!
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