ST21 Keel cooling option

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JoshuaAhab
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ST21 Keel cooling option

Post by JoshuaAhab »

Hi Jacques,

I've decided I need to spend the extra time and money for ST21 keel cooling due to the turbid water conditions in the Bay of Fundy.

Please let me know how much you extra charge for changing the ST21 cooling sytem from raw water to keel cooled and how I go about getting the changed design. Thanks.

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Evan_Gatehouse
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Re: ST21 Keel cooling option

Post by Evan_Gatehouse »

Are you going to use a commercial keel cooler (Walter or Fernstrum) or a home made one made from a bunch of pipes underwater?

If you use a commercial one, the manufacturers will make recommendations for the correct model. They will need to know which engine you plan to use, rates of water flow & temperature, and operating sea water temperature. From that they will recommend a model.

Caterpillar always had a good technical paper on sizing pipe type keel coolers - but their recommendations tended to give very long runs of pipe (conservative assumptions) which creates lots of drag compared to the commercial models.
designer: FB11/GV10,11,13/ HMD18/
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Re: ST21 Keel cooling option

Post by jacquesmm »

Thank you Evan.

JoshuaAbab, I agree with Evan's, you must start by selecting a keel cooler.
Pick and engine like the one StormBoatwaorks has = Kubota 3 cylinder 27 HP. Or pick a Yanmar, Beta etc.
Then contact a keel cooler manufacturer and ask for recommendations.
Once you have the specs for that keel cooler, I can tell you were to put it.
Once the cooler itself is in the hull, the connections are super simple, easier than seawater cooling.
I'll give you a couple of typical diagrams that will show how to install the keel cooler but it doesn't make much sense to discuss installation details since you don;t have the plans and would not understand what I say about frames XYZ and that much below baseline etc.
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JoshuaAhab
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Re: ST21 Keel cooling option

Post by JoshuaAhab »

Thanks for your responses Evan and Jacques.

Evan, It's best for me if I get a commercially available keel cooler so I'll check into the manufacturers you mentioned and see what they have to offer. I can probably cobble something together that might work, but I'd rather not test it out on the Fundy tides: I'd probably end up in the Gulf of Maine with a smoking engine.

Jacques ,I bought the ST21 plans a couple of months ago so I would know exactly what you're referring to if you gave instructions. However don't bother with that until I research the keel cooling options you mentioned. When I've decided what I'm doing I'll contact you again with that info so you can avoid redundancy in your responses. My plans are to follow the engine sizing, etc... as you've spec'd in the plans (except for the cooling option :wink: ).

With regards to sizing I note that Storm Boatworks has an engine with about one third more horsepower and a hull with about one foot more beam than you spec'd in the plans. Obviously it worked out for him. Do you have any thoughts on why those two particular changes were successful?

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Re: ST21 Keel cooling option

Post by jacquesmm »

I gave the links to those same keel coolers in another thread that you started. Please do not start several threads on the same subject.

The Storm Works boat is closer to the Atkins design Rescue Minor, my design is slightly different. I explain that in the study plans.
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JoshuaAhab
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Re: ST21 Keel cooling option

Post by JoshuaAhab »

So after a two plus year wait, a parcel arrived Monday. Gee, I wonder what it might be?
Image

I hope it's built as sturdily as it's packaged.
Image

Here are the relevant dimensions, Jacques.
Image

Is there any other info you require for the coolers inset housing scantlings?
Last edited by JoshuaAhab on Fri Aug 25, 2017 4:22 pm, edited 1 time in total.

jacquesmm
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Re: ST21 Keel cooling option

Post by jacquesmm »

Use the same thickness than for the hull, same tabbing than for the chines.
All what you need is a box around the keel cooler, with the area flush with the hull, nice backing plates where the bolts and pipes go.

Where you put that box is another point.
I can play with a surface on the hull (not today) but it should be on a flat part of the hull, deep, somewhere in the middle.
It looks like it is going to straddle a bulkhead.
Give me a day or two and I will post with a suggestion for the location. I ma really busy with a new version of the Tina for Port Aransas. Thye want a regular motorwell now, not a bracket anymore.
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JoshuaAhab
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Re: ST21 Keel cooling option

Post by JoshuaAhab »

I'll keep an eye out for your response.

Is this the Tina your referring to:
https://www.google.ca/imgres?imgurl=htt ... jwTfn4OoBg

or maybe this one:
http://www.atkinboatplans.com/Sail/Tina.html

They both have their own unique charm.

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Re: ST21 Keel cooling option

Post by jacquesmm »

I prefer the 1st one but it is a different one. It is a Tarpon Skiff from Port Aransas. A classic 23' inboard that I redesign for plywood-epoxy. I must make a presentation about it at the PlyWooden show in October. It is a commission from the local museum.
Port Aransas, TX, is on the path of hurricane Harvey and it looks bad. The boat show may be rescheduled but I keep working on the design.
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glossieblack
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Re: ST21 Keel cooling option

Post by glossieblack »

JA, great to see you've got the keel cooler! It looks an impressive piece of gear. :D

It will be interesting to so where Jacques recommends it be placed.

My amateur intuition is to run it forward from just forward of frame C, passing through the line of frame B. The box you glass in as part of the hull will make that whole area strong as.

Hope all is well at your end. :D
Currently building Jacques Mertens ST21 "Skinnydip". Boating adventures: Splash testing and using 'Skinnydip, as a basis of further building refinement; Adams 44’ sailing sloop "Great Sandy" (cruising and maintaining); Iain Oughtred Feather Pram "Mini Dip" (building); Jacques Mertens R13 "Wood Duck" (built and due for maintenance).

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