Friday, April 15, 2016

Launch Notice and Final Build Update - April, 2015

Pícara Sails!

Pícara, my Hazardous Zero-9 Merlin Rocket build and a Keith Callaghan design, was successfully launched and sailed this morning on Lake Travis, near Austin, Texas, USA. She gracefully sailed in light winds and quickly responded to mild gusts.

More photos, videos and a big blog update (after a year in hiatus) will come in the days ahead!

Pícara and I on launch day.

Pícara after her first sail.


A little bit of bubbly...

2015 - The Missing Files (Coming Soon!)

Varnishing The Decks

I selected EPIFANES Clear Gloss Varnish for being a traditional marine varnish, based on tung oil, phenolic-modified alkyd resins and having maximum U.V. absorbers. Being in Texas and going sometimes through significant temperature variations within a single day, not to mention the hot Texas Summer, I wanted a product that not only had the ability to handle our weather but also had superior flow, gloss and durability.

Preparation, per Epifanes, included sanding the deck and rails, and cleaning the clear epoxy thoroughly with alcohol and Epifanes Thinner.

Thinning ratio varies depending on the the number of coats applied. No sanding is needed if re-coated within 72 hrs.

I used a  good quality, clean, natural bristle brush and applied 4 coats of Epifanes varnish.

The product is very easy to apply and results are of great quality if instructions are followed.

I'm very pleased with the high gloss finish she now displays.

Pícara is now ready to handle the Texas weather. 

Rigging Pícara

Perhaps the most expensive aspect of boat building, and for a good reasons: Safety & Performance . It can't be said enough, choosing the right rigging hardware is key for accomplishing both. Buying parts as the build progresses can save money and help offset the big cash outlay at the end. Many of the suppliers have discounts throughout the year and I took advantage whenever possible.


For Pícara, I followed the recommended hardware listed in Keith Callaghan's drawings. In some cases where the exact part was not available in the US or in the UK, I consulted with Keith to select a comparable or better replacement. Hardware wood screw holes or machine screw holes were filled with epoxy and 404 High-Density filler, which is a thickening additive developed for maximum physical properties in hardware bonding where high-cyclic loads are anticipated

My main suppliers in the US are Annapolis Performance Sailing (online) and West Marine (local).

The Jib Cleat Brackets were fitted each with a Harken 150 Cam Cleat and a Harken 092 Cheek Block.

The cam cleats and the cheek blocks were bolted through the brackets.  

Bow tank deck covers fitted with stainless steel screws and recommended silicon sealant.

Ronstan 5/8" jib track x 18" fitted with corresponding track ends. 

Allen Webbing Bridges (2" Grey) were fitted on the plan landings to secure the buoyancy bags. 

Harken's swivel base with H150 Cam-Matic

Starboard side Harken H306 & H302 wire through deck blocks and covers for the shrouds and lowers.

Port side Harken H306 & H302 wire through deck blocks and covers for the shrouds and lowers.

The Tiller & Rudder Stock

These parts for the Merlin Rocket are relatively easy to source in the UK. In the US, however, this is not the case. After an extensive search  and contemplating the costs of buying one from the UK and shipping it over to the US, I decided to build my own until I can source one (new or used) for a reasonable price.

Having some extra marine plywood, mahogany and epoxy available from the build, made my decision a bit easier. The design requirements were simple; a breakaway system of relatively light weight but strong enough to house the rudder blade.

For the specific measurements and characteristics, I used advanced composite models as reference. Here, I start by laying out the rudder case assembly shape and fitting the 27mm mahogany spacers to house the 25mm rudder blade. Above the case is a pocket for the tiller carbon tube.

Once the spacers where fitted, I applied three coats of epoxy resin to the entire rudder case.
I proceed to select the pivot point and trace the breakaway turn radius.

After cutting the breakaway radius, I simulated the movement of the rudder inside the case and found out I had to make slight modifications to allow the free movement of the rudder blade.

Almost there... I had to cut the aft spacer of the rudder case at an angle where the trailing edge of the rudder blade swings inside the case during breakaway.

I drilled a 10mm hole at the pivot point on the rudder blade. Since the pivot point was at the trailing edge of the foil, I cut a 27mm carbon fiber spacer from a 10mm carbon fiber tube. Later, I inserted the carbon fiber spacer with epoxy and colloidal silica to make a strong rudder blade screw hole. I also applied three coats of epoxy resin to the exposed radius on the rudder blade.
Closeup view of the spacer and screw hole.

Here's a view of the rudder case with a slot on top for the carbon tiller tube and screw holes to secure it. The pintle and gudgeon screwed onto the case at the right location after fitting their equivalents on the transom. I also cut 10mm carbon tube inserts for the pivot screw holes.

An aft view of the rudder box showing the single block for the control line to keep the rudder down under way.

Final fitting test to ensure free movement on both directions before tightening the screws. 
Clearance test over the transom in all directions for the tiller's 1m x 30mm O.D. / 26mm I.D. carbon tube.

Installation of the Ronstan Battlestick carbon tiller extension and camcleat for the rudder control line. 
 The final article less the rudder blade.

The Sea Sure gudgeon and pintle mounted to take the rudder and tiller assembly.

For the transom hole flaps I used 2 mm clear Plexiglas purchased at my local home center. I used the full size transom drawing to trace the outline of my flaps with a marker. I decided on a simple single piece flap design.

Using a Plexiglas cutting tool, I proceeded to cut the excess material and sand the edges to a smooth finish. Then I shaped a curve at the bottom to clear the pintle upon installation.

 I fastened the Plexiglas flaps to the transom using 2 stainless steel wood screws.

Using shock chord and the smallest line I had, I created a simple string system to keep the flaps open or closed as needed.

The Hoop

I chose to make the hoop of my Merlin Rocket out of carbon fiber tubing. The O.D. is 30 mm and the I.D is 26 mm. The 2 mm thick wall makes it a very strong tube. Perfect for the job. 

The height of the hoop is approximately 90 cm. The width at the top is about 30 cm. The vertical carbon fiber tubes are inserted through the thwart via holes custom cut to fit the tube at an angle. The location of the through holes was estimated based on the construction photos of Wicked, MR 3708. 

The vertical pieces are slightly angled towards the inside at the top so I had to design its construction to enable me to disassemble and remove the hoop when needed.
I used DragonPlate's 1" aluminum modular tube connectors for this assembly.

The DragonPlate 1" modular tube connectors ship with the proper micro filler to mix with epoxy and bond the aluminum connector to the carbon fiber tube. I used 2 male connector ends on the horizontal section and 2 female connector ends on the vertical sections. 

Rear view of the finished hoop prior to fastening.

Mounted on the front horizontal section of the hoop is a 13mm Harken Low-Beam Pinstop Track where a 13 mm Micro CB Traveler Car holding 2 Harken 29 mm T2 Soft-Attach Blocks.

A little closeup of the car and block assembly.

Next? Finish Rigging Pícara!

Sunday, March 8, 2015

January, 2015

Finishing the Spinnaker Chute

In retrospect, I should have provisioned for a more holistic approach to finish the spinnaker chute and make sure I designed a 1 piece cap to fit nicely over the rough opening, covering the breasthook, the stem and the gunwhales. I envision this piece now of solid Mahogany stock with pre-finished rounded edges so that only minor touch ups are needed afterwards.

Well, hind sight is 20-20. My reality called for adding small pieces of solid Mahogany stock to round off the corners and line the sides of the opening. 

Adding the pieces to round the corners. I also clamped an L-shaped jig over the deck from the gunwhales to provide a surface to clamp the corner pieces from. Also placed a wood block at the stem to prevent the clamps from damaging the deck.

Fitting the side pieces.

Next, I bevel the deck at the bow to make room for the nose cap.

Epoxy Coating The Deck & Strakes

Prior to varnishing the deck and rubbing strakes, I apply 3 coats of West System 105 epoxy with 207 Special Clear Hardener. This will be the base for the layers of Epifanes clear varnish I'll apply once the average daily temperature warms up within the manufacturers recommended range.

View of the foredeck.

View of the side decks.

Aft view from the bow.

View of the foredeck and the carlins from the transom.

View of the spinnaker chute opening.

Full view from the bow.

Carlin detail on the aft port side as it turns around to the transom.

Carlin detail on the aft starboard side as it turns around to the transom.

Carlin detail on the port side as it turns around from the side deck to the foredeck.

Carlin detail on the starboard side as it turns around from the side deck to the foredeck.

Foredeck after applying 3 layers of epoxy with West Marine 207 Special Clear hardener.

Thank you for visiting!