ST21 Keel cooling option

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JoshuaAhab
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Re: ST21 Keel cooling option

Post by JoshuaAhab »

I thought more pictures might help in the event it has a bearing on proper intallation. The total length of the cooler is actually 1011 mm with the zinc attached. Also it's a U-Flow unit with the inlet and outlet on the same end. Let me know if one orientation is better than the other: either inlets forward or inlets aft.

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My amateur intuition is to run it forward from just forward of frame C, passing through the line of frame B.
We'll wait for Jacques final word but I believe your intuition might be correct. A reread of the keel cooling section of the building notes confirms your suspicions.
Hope all is well at your end. :D
Everything's great here at my end. Next week I embark on a major career change into the marine field. So I'm part :D regarding the adventurous aspect; and part :cry: regarding the amount of work involved for the next few months. After that the job allows for half the year on and the other half off. More free time than I have now at any rate.

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Re: ST21 Keel cooling option

Post by jacquesmm »

I don't think that the location of the connecting pipes matter.
I am busy witha little project now (LM18 round chine option) but I will try to remember looking for a location tomorrow.
I will design the envelope of your keel cooler and slide it along the hull to see where it can go with minimal drag.
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Evan_Gatehouse
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Re: ST21 Keel cooling option

Post by Evan_Gatehouse »

Yes, the orientation of the inlets/outlets doesn't matter. Make sure your pocket is big enough to allow you to scrape oysters off the cooler if they ever grow there :0
designer: FB11/GV10,11,13/ HMD18/
SK17,MM21/MT24

JoshuaAhab
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Re: ST21 Keel cooling option

Post by JoshuaAhab »

Bump.

Hi Jacques,

Did you get a chance to work out the location of the cooler housing as well as it`s scantlingsÉ

JoshuaAhab
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Re: ST21 Keel cooling option

Post by JoshuaAhab »

Bump. Hi Jacques, Did you get a chance to work out the location of the cooler housing as well as it`s scantlings

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OrangeQuest
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Re: ST21 Keel cooling option

Post by OrangeQuest »

jacquesmm wrote: Mon Aug 28, 2017 5:14 pm I don't think that the location of the connecting pipes matter.
I am busy witha little project now (LM18 round chine option) but I will try to remember looking for a location tomorrow.
I will design the envelope of your keel cooler and slide it along the hull to see where it can go with minimal drag.
JoshuaAhab wrote: Fri Oct 05, 2018 11:57 am Bump. Hi Jacques, Did you get a chance to work out the location of the cooler housing as well as it`s scantlings
:)
"that it isn't just an ordinary sort of boat. Sometimes it's a Boat, and sometimes it's more of an Accident. It all depends." "Depends on what?" "On whether I'm on the top of it or underneath it."
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jacquesmm
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Re: ST21 Keel cooling option

Post by jacquesmm »

I did not but it is very simple: the "box" that contains the keel cooler should be built the same way than the hull bottom, not lighter. The size will be a few inches larger than your keel cooler for a good flow. The location can be anywhere with a good water flow. That means in the keel side panel, lengthwise location about under the console. I have seen one ST21 rigged that way and cooling is perfect (with a Fernstrum cooler).
Too much forward will not get a sufficient flow, too far aft may create a vacuum.

If you go back to the Rob White web pages linked from the study plans, you can see that he used a plain 6' long copper pipe located about where I advise it. His is not an ST21 but it's the same type of boat, same tunnel.
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JoshuaAhab
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Re: ST21 Keel cooling option

Post by JoshuaAhab »

OK.


OrangeQuest; Thank you for the extra bump. :D

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Re: ST21 Keel cooling option

Post by jacquesmm »

BTW, I assume that you have seen the Fernstrum keel cooler installation notes?
Here:
https://www.fernstrum.com/products/grid ... n-options/
Here is their text:
Recessing a GRIDCOOLER Keel Cooler streamlines the installation and provides significant protection from potential damage. Independent tests conducted at the Vienna Model Test Basin have shown that drag is negligible when the unit is recessed into a ship’s hull. The position of the recess can be located on the side or bottom of the hull. This type of installation is common in new projects and ideal for fast-moving vessels.


It is very simple.
What I describe is the recessed installation but I recommend a little more room around for cleaning as Evan suggested.

I found more here:
http://www.duramaxmarine.com/pdf/DURACo ... lation.pdf
same type of installation.
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JoshuaAhab
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Re: ST21 Keel cooling option

Post by JoshuaAhab »

Thank you, Jacques. You've provided me with sufficient guidance to proceed.

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