The believed abstraction of a 12 foot clinker dinghy.

[Breakaway]

Lovely!


Sent from my iPhone using Tapatalk Pro

[KenStocker]

Looks more stunning every day...in spite of your bad day! I inadvertently clicked on the first page of your thread the other day, and I had forgotten what you started with. Everyone ought to go back to picture #1, just for fun. Makes what we are looking at now all the more incredible! Thanks for posting, it's fun to watch you be creative in ways of doing things that I would never even dreamed of. Part of what we are lucky to have in this forum.

Ken

[Max F]

I just second Ken
Man that looks stunning.
Haha, I know this mishaps like yours on the centerboardcase.
Smashed my drill on the floor and yelled some mean stuff a few days ago.
God, was I angry.
But as a wise old boatbuilder once told me.
**** happens, but no one will ever recognise if you are an able craftsman.

Cheers
Max

[Mike1902]

Lovely!
Sent from my iPhone using Tapatalk Pro

Thanks Kevin, glad you like it.
Cheers.

Looks more stunning every day...in spite of your bad day! I inadvertently clicked on the first page of your thread the other day, and I had forgotten what you started with. Everyone ought to go back to picture #1, just for fun. Makes what we are looking at now all the more incredible! Thanks for posting, it's fun to watch you be creative in ways of doing things that I would never even dreamed of. Part of what we are lucky to have in this forum.

Ken

Thanks very much Ken for those words of appreciation.
It was a very nice post to read this morning, so much so, I read it aloud to my wife.
Cheers.

I just second Ken
Man that looks stunning.
Haha, I know this mishaps like yours on the centerboardcase.
Smashed my drill on the floor and yelled some mean stuff a few days ago.
God, was I angry.
But as a wise old boatbuilder once told me.
**** happens, but no one will ever recognise if you are an able craftsman.

Cheers
Max

Thanks Max.
A boss from days gone by told me that "A carpenters true skill is measured in their ability to cover up their mistakes".
The DB case is more of an annoyance about delay than anything else, the blemish is nothing a bit of sandpaper and a full repaint cannot fix.
Your drill however, Max, may require a little more surgery by the sounds of it.

Your launch date is getting close btw Max, not that you need reminding of the fact

Cheers,
Mike.

[Max F]

I was lucky, no damage.I was working outside. So it got smashed onto the grass.
Some enthusiastic neighbours were full of questions. I got distracted and drilled a to big hole.
It wasnt that big an issue, more an anoying extra delay to fix it...

Thanks, I nearly forgot hahahaha.
I´m at good pace and still confident that all will be ready

Cheers
Max

[Larks]

She’s a work of art Mike - nice choice of colour

[Mike1902]

She’s a work of art Mike - nice choice of colour

Thanks Greg, much appreciated.
Admittedly, there were a few colour combos considered, that were, how shall we say, "a little out there" but I'm pleased with the choice also.
The other thing is, if I ever get tired of it, I can change it.

Cheers,
Mike.

[Mike1902]

So, after a bit of toing and froing a decision has been made in regard to a rudder configuration.This is the first option that will be constructed.

IMG-7486.jpg

The chord will be 250mm (10"), the overall length 1 metre ( 3'4") with approx. 625mm (2'1") below the waterline.
The rudder will be raked about 20 deg off vertical ,forward at the foot,it will slide into a cassette that will also be foil shaped.
The cassette will be made in the above water profile of a barn door rudder.

IMG-7483.jpg

The two foil profiles shown in the above image represent the 250mm (10 7/8") foil shape which is perpendicular to the rudder edge and the 270mm (10 5/8") foil shape which is the shape of the rudder taken through the horizontal as it hangs on the transom.
To achieve a 15% foil thickness to chord ratio in the horizontal plane (direction of water flow) the actual rudder has to be made with a 16.2% ratio.
This gives a 40.5 mm (1 9/16") thick rudder across a 250 mm chord.
The keel will be trimmed flush with the transom btw.

IMG-7482.jpg

https://cci.one/site/marine/design-t...45898437500000
I used the calculator in the link above to obtain the measurements for the two profiles.
The profile is quite thick to construct with the method that I used on the dagger board, probably to much, there would be a risk of cracking the plywood.
So the plan is to make a laminated Kauri timber leading edge that the ply will attach to, as shown below. There will also be a laminated carbon wrapped spar running the full length with a carbon tape U channel attached to help stiffen the ply.

IMG-7488.jpg

The complete rudder will then get the whole epoxy cloth wrap, fill and graphite treatment.
Making the cassette will be even more fun.

[Peerie Maa]

^ Did you remember this advice about the cassette?

You could make it stronger by taking the cassette down to the bottom of the skeg.
Forward sloping rudders also work.
Attachment 111656
Less likely to break if you touch bottom.

I have just gone back through the other thread and found your comments.
At least take it down to the bottom of the transom, it will not be in clean water there, and so will be stronger but with no downside.

[Mike1902]

Crikey Nick, you are making me reveal all my secrets

The scenario:- wanting the look of a barn door rudder without it acting like a barn door rudder.

The issue I'm having before finalising the cassette shape is where the waterline actually is.
I only have the red painted bottom in the photos in post #1 to go off.
The boat was fairly heavy with the old centreboard/rudder setup and now with my new arrangement it may come in a little lighter.
I have of course added extra timbers which may counteract that so I've just stuck with the original line.

If I finish the bottom of the cassette to high then it will look odd sitting out of the water, to low then I think it may interfere with the feel of the tiller.

So here's the plan, add some depth but shape it foil like.

IMG-7492.jpgIMG-7493.jpg

I have this drawing template that I have been using as a guide to gauge the overall look.

IMG-4307.jpg

Imagine this shape with a rudder protruding through the bottom of it.

The cassette itself will be made from 3 laminated panels each side, similar to how I made the dagger board case but the panels will finish flush on the outside.
The leading edge and tail will be solid laminated timbers that the panels will rebate into.
The laminated tiller will fork and run down each side along the top edge of the cassette.

IMG-7490.jpg

This drawing shows basically how the cassette will attach to the transom.
The pin will lock in somehow, still working on that one.

[Peerie Maa]

Crikey Nick, you are making me reveal all my secrets

The scenario:- wanting the look of a barn door rudder without it acting like a barn door rudder.

The issue I'm having before finalising the cassette shape is where the waterline actually is.

When she is moving, any water above the bottom of the transom will either have separated or will be dragged forward by the transom.
So you need not obsess about any part of the rudder cassette above the transoms bottom edge.

[Mike1902]

When she is moving, any water above the bottom of the transom will either have separated or will be dragged forward by the transom.
So you need not obsess about any part of the rudder cassette above the transoms bottom edge.

You are spot on there Nick and thank you for your pointers.

Cheers,
Mike.

There is a somewhat debated architectural phrase "Form follows function", that was expanded upon by Frank Lloyd Wright that "Form and function are one".
Wright also said that "Less is more when more is no good".
The point I'm making in regard to my design is that even though a lengthened rudder head may be stronger, what I have come up with will be adequately strong enough without the chunky form of an unnecessarily oversized and possibly weightier rudder support.
This particular dinghy has a low freeboard and almost catboat like proportions, hence the faux barn door rudder idea and through transom tiller, the sheer does however lift abruptly at the stern, so the profile of a rudder head continuing above the top of the transom would look (to me) to long/high and out of place.
It would also interfere with my intended mainsheet arrangement.

Now that I have a clear plan, progress was made on the rudder this weekend.

IMG-7496.jpg

Two lengths of 7 laminated kauri strips were glued up and then dressed to size. One was wrapped in carbon fibre then wrapped again tightly with peel ply. This is the spar that will run down the inside of the rudder.

A profile was then drawn of the rudder blade leading edge with rebates to take the ply skins.
An angle was established for the table saw blade to rip the rebates.

IMG-7498.jpgIMG-7501.jpg

Using a square block of similar dimensions to the carbon fibred spar and a couple of ply strips placed in the rebated spar, the foil shape was checked against the naca profile.

IMG-7505.jpg

[Mike1902]

Progress on the rudder foil this week.

IMG-7511 (1).jpg

The ply panels were glued into the rebates of the laminated leading edge.
The laminated spar was wrapped in carbon fibre.

IMG-7513 (1).jpg

As a precaution, a glass reinforcing strip was laid along the forward third of each panel. This is the area that cracked when I made up the dagger board.

IMG-7516.jpgIMG-7517.jpg

Spacer blocks were also added along the spar, this not only held the spar at the correct height, square and plum, but also provided support to the ply as it was bent around the spar.
The ply that is being used is Meranti. This was purchased mainly for use on the decks, watertight compartments and strake repair because it is strong, durable and stable.
If I was to do this again I would use Gaboon (Okoume) ply as it is a little more flexible.
I did not want to introduce moisture with steaming, wetting or whatever, so these extra precautions were the compromise.

IMG-7536.jpg

Today was the big glue up. The inside of the panels were primed with epoxy, the spar edges and the spacer blocks were coated with a 413 filler/epoxy mix and placed between the panels.
The panels were then squeezed together with clamps and timber strong backs to apply an even pressure along the rudder.
Screws were then used to hold the panels against the spar and the clamps removed. Carbon fibre was then laid into the U against the spar and up the sides of the panels as seen in the above image.
The trailing edges, which had been chamfered and covered with 413/epoxy, were then pulled together again with strong backs and clamps.
The leading edge will now be shaped into the foil profile.

[Andrew Donald]

I nearly choked when Nick used the phrase “no need to obsess” in this thread.

keep up the “interesting obsessed” work Mike

[Mike1902]

keep up the “interesting obsessed” work Mike

Thanks Andrew, will do.

Cheers,
Mike.

[Mike1902]

Foiled again.

IMG-7543.jpgIMG-7542.jpg

The front and back edges have been shaped up and squared off.

IMG-7546.jpgIMG-7539.jpg

A profile template was run down the length of the board to check the consistency of shape.
Managed to get pretty close to the desired form.

[KenStocker]

I will be thrilled if mine turns out to be anywhere near that "pretty close". Lookin' good!

Ken

[Mike1902]

I will be thrilled if mine turns out to be anywhere near that "pretty close". Lookin' good!

Ken

Thanks Ken. The other side required a little fairing to fill out the curve but nothing major.

Progress this week .

Carbon fibre reinforcing along the trailing edge.

IMG-7556.jpg

Glued two kauri blocks together to make up the foot and glued in a 1/2 inch thick triangular block to fill up the space at the bottom of the rudder.

IMG-7561.jpgIMG-7565.jpg

The gluing surfaces were scored with a sharp blade to aid in the mechanical adhesion of the two parts.

The foot block was then faired into the rudder profile.

IMG-7569.jpgIMG-7571.jpg

There will be no carbon fibre strip along the leading edge or around the base as per dagger board.
The leading edge is a fairly solid timber member in this case and the foot will be wrapped in a dynel boot instead.

The rudder will be completely encased in fibreglass cloth and finished with a graphite epoxy mix as per dagger board.
The top of the blade will be trimmed to the shape of the cassette when that has been completed.

[Mike1902]

Mid Friday afternoon I started glassing up the rudder blade. Throughout the entire glassing, dynel and filling process, through to graphite coating, 205 fast hardener was used to speed up the process... and a heater.
Using the same method to support the rudder blade as I used for the daggerboard allowed me to glass both sides of the blade at once using the same batch of epoxy.
Friday early evening:- 50/50 mix 410 filler and epoxy hot coated onto both sides.
Friday late evening the glass was trimmed along the trailing edge and around the foot while in a green state.
IMG-7580.jpg

Mid day the following day the fairing was completed and the glass cloth tapered off around the foot to form a scarf for the dynel cloth.

IMG-7589.jpg

Dynel was epoxied around the foot overlapping the glass cloth.
The epoxy was applied with a chip brush, just enough to saturate and hold the cloth in position. The dynel formed nicely around the foot in one piece.
Mid afternoon a 50/50 mix of 410 filler and epoxy hot coat was liberally brushed into the weave then left overnight in a warm environment.

IMG-7592.jpg

Next day around mid day the fairing/dynel was sanded back being careful not to sand through the glass weave but maintaining a flush overlap.

IMG-7605.jpgIMG-7611.jpg

Throughout the rest of the day I managed to place two coats per side of epoxy/graphite mix with the help of the fast hardener a heater and a core flute panel to contain the heat somewhat.
Masking tape was placed around the perimeter to act as a drip edge. One side was completed before rotating the blade to complete the other.
This will be left for a week before finish sanding.
I now have a pattern for the cassette laminations.

[John B]

I'm out of superlatives as usual.
Where are you buying the graphite these days?

[Mike1902]

I'm out of superlatives as usual.
Where are you buying the graphite these days?

As usual? John, the way you articulate through your writing has often had me thinking "this guy should be penning books" ,especially humorous ones.
Go on, fire up that laptop.

As for the graphite, Adhesive Technologies NZ Ltd in Henderson have it.

Thanks John.

[Alan71]

Hello Mike,

The way you do each step with such precision is truly amazing to me.

I continue to seem to find every possible pitfall.

I enjoy seeing how you work... and what you produce. Thanks for taking the time to take the photos and describe what you're doing.

Regards,
Alan

[Mike1902]

Hello Mike,

The way you do each step with such precision is truly amazing to me.

I continue to seem to find every possible pitfall.

I enjoy seeing how you work... and what you produce. Thanks for taking the time to take the photos and describe what you're doing.

Regards,
Alan

Thanks Alan, my pleasure, glad you are enjoying the process.

As for pitfalls, had a couple myself this weekend.
Air bubble in the epoxy dispenser, had to redo that one.
Vacuum hose detaching itself from the sander without me noticing until the room started to get foggy, thought it was my glasses steaming up from the face mask. Had to open up all the windows ,turn the fans on and lose all the heat out of the workshop for that one.
%*#! happens, you just fix the problem best you can, be aware for next time and move on. It's all part of the creative experience

Cheers,
Mike.

[timo4352]

Thanks Alan, my pleasure, glad you are enjoying the process.

As for pitfalls, had a couple myself this weekend.
Air bubble in the epoxy dispenser, had to redo that one.
Vacuum hose detaching itself from the sander without me noticing until the room started to get foggy, thought it was my glasses steaming up from the face mask. Had to open up all the windows ,turn the fans on and lose all the heat out of the workshop for that one.
%*#! happens, you just fix the problem best you can, be aware for next time and move on. It's all part of the creative experience

Cheers,
Mike.

Love it!!!
We have all been there!

[John B]

As usual? John, the way you articulate through your writing has often had me thinking "this guy should be penning books" ,especially humorous ones.
Go on, fire up that laptop.

As for the graphite, Adhesive Technologies NZ Ltd in Henderson have it.

Thanks John.

Articulate? You mean like one of those boatramp backing youtubes where it all goes pear shaped and tangled...heh.
Thanks Mike, and thanks re AT, I've devolved into buying what I need at the chandlery due to a lack of planning and foresight.

[Larks]

New Zealand’s version off a “warm environment”




I never cease to be knocked over by the work that you are doing Mike - inspirational!!

[Mike1902]

Love it!!!
We have all been there!

Ha, yeah, not the first time the hose has dislodged either. May be time to heed my own advice.

Chalk and cheese rudders.
IMG-7614.jpg
Bit of trivia.
New blade weighs 2.7 kgs (6 lbs)
Old barn door 4.9 kgs (11lbs) Yes, those are lead weights dotted through the timber.


IMG-7624.jpg

In the photo above the waterline is represented by the steel rule.
The rudders are placed as they would be when fully down and at the appropriate angle to that waterline off the transom.
The area of the old rudder below the waterline is 75 cm2 (9 sq inches) bigger.
The CLR has moved forward a tad, good I suppose, closed the gap on the C of E , especially with the new bowsprit idea.
First day on the water is going to be very interesting.

[Mike1902]

New Zealand’s version off a “warm environment”




I never cease to be knocked over by the work that you are doing Mike - inspirational!!

Haha...well it is June after all.
In saying that we hit 21 deg C last Wednesday, right balmy it was.
Thanks for the plaudit Greg.

Cheers,
Mike.

[Mike1902]

With the rudder foil complete, it can now be used as a pattern for shaping up the two curved inner panels of the rudder cassette, a similar construction process to the dagger board.

IMG-7625.jpg
I was hoping to get away with laying the trial strip around the forward curve dry, without breaking, but that wasn't going to happen, so that part of the timber had to be soaked in water for 5 minutes before clamping.
Once it was established that would work, the job was then to make 108 of them.

There will be four panels in total, the two extra panels will form the outer overall curve of the cassette.
Each panel will be made up of 3 layers of 9 strips, which is 27 strips of Kauri 50mm (2") wide and 2.5mm (3/32") thick.

IMG-7636.jpgIMG-7635.jpg

The left over stock from the sole boards worked out great for making up the strips. The stock was 12mm (1/2") thick, this was ripped into 50mm wide lengths which were then cut to the needed length of the panels.
These shorter lengths were then set on edge and ripped on the band saw into 3mm thick (1/8") pieces, gaining three per length.
These were then thicknessed to 2.5 mm.

IMG-7631.jpg

Six panels were then made up by edge gluing the 9 strips together, some panels had different width end pieces so the joins would be staggered when the 3 layers get laminated together.

IMG-7639.jpg

In the above image three panels have had their leading edges soaked in water for 5 minutes before being pressed around the rudder blade and left to dry before glue up.

[Max F]

Wow Mike
Good progress and good read too.
I only have to be absent a couple of days and you moved along on a blast.

Cool!
Cheers
Max

[Mike1902]

Wow Mike
Good progress and good read too.
I only have to be absent a couple of days and you moved along on a blast.

Cool!
Cheers
Max

Thanks Max.
Your trip looked great. Your little ship kept you safe and sound. Well done.
Cheers.

The two inner panels have now been formed.
Using thin layers limited any spring back, in fact there was virtually none at all.

IMG-7654.jpgIMG-7653.jpg
The leading edge of each panel will be trimmed back to a line about 20mm from the front edge of the foil.
The cassette will have a solid timber nose that the panels will bet let into.

IMG-7642.jpgIMG-7643.jpg
The panels were checked for uniformity, good enough.
Now onto making up the forms for the outer panels.

IMG-7658.jpg

This full sized plan shows the intended layout of the panels and the overall look of the cassette.
How the top and bottom edges will be constructed is still floating around in the ether.
The small rectangular spacers shown are actually going to be a diagonal grid or a truss of sorts that will help spread the load between the two panels, which by their shape and construction are very rigid.
The solid timber parts will also be laminated.

[Max F]

Aah a pleasure to follow.

[Mike1902]

Aah a pleasure to follow.

Thanks Max, here is a little more.

A quick rudder cassette progress report.

IMG-7710.jpgIMG-7708.jpg
The images above show the starboard half of the cassette.
Each half is made up of six structural pieces. The leading edge is made up of three laminates, the tail piece two laminates, top ring frame ten laminates and the bottom ring frame eleven laminates.
The bottom frame strips were soaked in water for 5 minutes then bent around a form and left to dry for 24 hours before gluing.
The inner panel is shown dry fit and the outer panel will fit into the rebates along the leading edge and tail pieces.

IMG-7715.jpg
The above image shows the rebates in the ring frame that cover the panel end and also the rebates along the leading edge and tail pieces that will house the outer panel.
It may look a little chunky in this photo but once the outer panel has been fit the ring frames and tail piece will be shaped to it.
There is still some tweaking and cleaning up to do before final glue up.

IMG-7701.jpgIMG-7707 (1).jpg
In the left image above the rudder has been placed into the slot to check the clearances for glassing, filling, graphite etc.
The right image shows the splines that help line everything up plus the inner panel fit into the rebates.
A short spline will also be inserted into the hole formed by the tail pieces.

[Max F]

That will be an awesome lookin rudder Mike
Very elaborate and sophisticatet.
Can´t wait to see more

Cheers Max

[Mike1902]

That will be an awesome lookin rudder Mike
Very elaborate and sophisticatet.
Can´t wait to see more

Cheers Max

Thanks Max.
I'm very pleased with how it is turning out.
I have finished dry fitting the four ring frame pieces top and bottom.
This evening, the leading edge and tail pieces were glued onto the inner panel then clamped on a flat and level surface to avoid twisting.
Tomorrow the ring frames will be permanently attached, the next stage is to fit the outer panel then shape the exterior into a nice hydrodynamic shape.

Cheers,
Mike.