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Ocracoke 20 in OZ


lenm

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I have a question about this specific design.  Most of these 20s look to have the sheer break close to mid-ship.  But a couple, this one included, seems to have the break about 1/3 from the stern (as they should).  I always think the break is too far forward, but lenm's example here is absolutely perfect.  I think Shay built one that had the sheer pulled back also...not sure.

 

So the question is, are there two different plans?  The boat in this thread is as fine an example as has been presented.

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Jay I guess I need to tackle this post.

 

To the best of my knowledge, I am not aware of anyone deliberately altering the sheer except for Emvrin in Malta who changed it from a CC to a cuddy, although I am sure that some may have gotten it wrong.

 

Shay did indeed build a 20 but I recall that after it was built he confided that stretched the boat. I am not aware that he otherwise altered the sheer. He might chime in.

 

The trouble with pictures is that they play tricks depending on camera angle, boat trim, focal length, magnification and lighting. Not to mention the finishing touches of the builder, like tapering of trim pieces paint lines, striping, rounding of corners and blending of faces can turn a rather agricultural look into a fine vessel or vice versa.

 

I checked the numbers and the break of the sheer is 85 1/2" forward of the outboard edge of the transom which is only slightly more than your 1/3 rule. It has never been altered.

 

When designing a boat we still have to follow the FFF rule, form follows function. Don't get me wrong, aesthetics play an important part. When designing the sheer break, we start by putting it where we think it should be, then the fighting begins. Is there enough length between the aft deck and the sheer break to land a large fish with the fisherman and crew with a gaff? In this case there is 62". Will the tumblehome interfere with landing that fish? Getting the cockpit height right so that it does not back flood when backing down, but no more so that the cockpit has enough height to be safe but no higher than necessary for landing that fish.  Where is the CB/CG in light and loaded trim, the console and helmsman seat, framing and having enough structure to take reasonable abuse without being overbuilt, positioning the tanks to meet the CG? Can it be built by first time builders with good guidance etc. etc..

 

Having said all that, it still gives me great pleasure to see non boat builders like Len turn out such nice boats.

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Thank you very much for your answer, Mr. Graham.  In the past, I would have talked with our friend Buck about these design intricacies over lunch (since I fed him nearly every day of the week) ... but none of us have that pleasure any more.  It, apparently, is more optical illusion than anything else.  I can't imagine a better example than what Len has produced.  Thank you for your information.

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  • 3 months later...

As promised, my particular performance specs incase anyone is interested / building an OC20.

Motor: Yamaha 150hp XCA (2800cc) Digital Electric Control

Prop: Yamaha Reliance 3 blade Stainless 17m 14 1/4

Trim Tabs: Bennett Bolt 9x12

Crew: 3

Fuel: 150 Litres

WOT: 40 Knots at 6000RPM

Cruise: 20-25 knots at 3400-3800rpm

Fuel: 17-20 Litres per hour at cruise

Just did a 150km round trip to the top of Fraser Island and we only used 74 Litres of fuel total.

DJI_0796.jpg

My Movie 14.jpg

capture-20210615-135156.png

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  • 2 months later...
  • 4 weeks later...
On 8/21/2021 at 4:26 AM, Justin C said:

@lenm Congratulations! She's an amazing looking boat.  This is really the boat I want to build (but need space). Thanks for sharing the journey with us. 

 

Did you ever finish the model you built to match the finished boat?

Thanks Justin!

It sure is a journey if lots of time love and care is put into a build (such as your project and some of the other build on this forum)

I still need to finish the model but it will be done soon.

I have had the boat on the water for several months now and have had 3 offers to purchase it. People stop me at the gas station, the boat harbour, out fishing, and even knock on my front door to ask if they can have a look over it.

I never intended it to be anything more than a tool for my fly fishing and family adventures - so humbled by all the compliments. 

Graham is certainly a talented designer and am greatful he bring designs like this to hobby builders such as ourselves.

Building a boat is so rewarding, is certainly trumps any other achievement ive personally achieved in my life like university/masters degrees etc. 

Look forward to following others builds such yours now

 

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  • 2 years later...
On 2/26/2021 at 3:52 PM, Designer said:

Jay I guess I need to tackle this post.

 

To the best of my knowledge, I am not aware of anyone deliberately altering the sheer except for Emvrin in Malta who changed it from a CC to a cuddy, although I am sure that some may have gotten it wrong.

 

Shay did indeed build a 20 but I recall that after it was built he confided that stretched the boat. I am not aware that he otherwise altered the sheer. He might chime in.

 

The trouble with pictures is that they play tricks depending on camera angle, boat trim, focal length, magnification and lighting. Not to mention the finishing touches of the builder, like tapering of trim pieces paint lines, striping, rounding of corners and blending of faces can turn a rather agricultural look into a fine vessel or vice versa.

 

I checked the numbers and the break of the sheer is 85 1/2" forward of the outboard edge of the transom which is only slightly more than your 1/3 rule. It has never been altered.

 

When designing a boat we still have to follow the FFF rule, form follows function. Don't get me wrong, aesthetics play an important part. When designing the sheer break, we start by putting it where we think it should be, then the fighting begins. Is there enough length between the aft deck and the sheer break to land a large fish with the fisherman and crew with a gaff? In this case there is 62". Will the tumblehome interfere with landing that fish? Getting the cockpit height right so that it does not back flood when backing down, but no more so that the cockpit has enough height to be safe but no higher than necessary for landing that fish.  Where is the CB/CG in light and loaded trim, the console and helmsman seat, framing and having enough structure to take reasonable abuse without being overbuilt, positioning the tanks to meet the CG? Can it be built by first time builders with good guidance etc. etc..

 

Having said all that, it still gives me great pleasure to see non boat builders like Len turn out such nice boats.


Out of interest how much was this boat stretched by. Was it stretched in length alone and was it difficult? 

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