June 27, 2014

Composites Aboard - Technical Post

I built a good portion of Ceilydh, using about 100 gallons of epoxy. So it would be fair to say I know a bit about composite boatbuilding and repairs.  Here is a sampling of what we carry aboard, and why we may use some specific items.


1 & 2 - Epoxy resin and hardener. Unless you have a very low budget or are building a new good size part, skip polyester resin. It's weaker, less waterproof, stinks, and has a limited shelf life.  I get very fidgety unless I have 4L or more aboard.  That's enough for a good sized repair job.

Brand preferences: 
  • West System is expensive so I avoid it. 
  • Epiglass is very sensitive to mix ratio errors so I don't like it either. 
  • System 3 is nice. 2:1 mix ratio.
  • www.bateau2.com sells an economical house brand called e-poxy I've used with good success. 
  • Currently I'm using Ampreg 22 with slow hardener.  Like it a lot. Dyed resin and hardener helps to make sure you mix it well. Hardener is nice and slow, even in summer temperatures (yes I know it's winter here). 

    Whatever type of epoxy you use, get the SLOW hardener if you're cruising tropical areas.
3 & 4 - G/flex - a wonderful thickened epoxy glue made by West System. Only epoxy that I know that will reliably stick to most plastics. We have a water tank fitting held in a polyethylene tank with the stuff. 1:1 mix ratio which is very forgiving, and it's often what I reach for when doing a very small batch. 

5 - Marinetex - inherited from other cruisers. Works fine, is quite hard but mix ratio is tricky with the small bottle

Not shown - little tubes of JB Weld. Useful for engine repairs because it is heat tolerant.

 6 & 7 - epoxy fairing putty. Useful for big fairing jobs (I'm building a new rudder right now). Usually I mix my own fairing compounds but the pre-prepared stuff is nicer, if more expensive.

8 - colloidal silica. Used as a thickening agent and to make a gluing compound. About 2:1 silica/epoxy resin ratio by volume with make a very stiff mixture.  You can buy a huge sack for about $80 from commercial fiberglass suppliers (about the size of 3 x 20L buckets). Compare that to the price that West charges for little carboard tubes of the same stuff...

9 - microballons. Lightweight balloons that are easy to sand. You still need to add some colloidal silica to stop the fairing mixture from slumping.

10 - milled fibers. Highest strength structural filler but use with discretion as the resulting mixture will be very lumpy. I only use this on items that have to take really big loads like a sloping winch base mount.

Mold wax - used to wax irregular shaped molds. A little can of it will go a long way. A hard car wax can be used but make sure it has no silicones (they stop stuff from sticking)


1 - Biaxial stitched cloth is my normal choice of fiberglass for all purpose repairs and construction. It's about 40% stronger than woven cloth of the same weight and drapes better if you use the +/- 45° style. 
  • I almost never use roving because stitched cloth is so much better for most applications
  • I almost never use mat unless it's for a very small part with tight contours. It sucks up resin like a sponge and is very weak.
  • I do use light woven cloth as the final layer on parts where I want a nice cosmetic appearance
 2 - I usually have some 4" wide x 6 oz (100mm x 200 gram/m2) woven tape on hand. Used for tabbing parts and joints. It's tidy to use. I wouldn't use it to rebond a main structural bulkhead but for everything else 1 - 3 layers will provide a strong bond

3 - woven braided sock - this is pretty esoteric stuff. I used it to build some new glass/carbon tillers. You slide it over a form like a sock and it will stretch to suit the diameter and take gentle bends. Not really required for most cruisers!

4 - carbon twill about 7.5 oz/250 gram/m2. This is a woven weave and it always looks nice. If I'm building a carbon part with an exposed weave I'll use this as the top layer for looks. Drapes very easily. Very costly.

5 - carbon unidirectional fiber - 9 oz/300 gm/m2. Left over of a 500' roll from when I was building the boat. I use this when I want a part to resist bending in one direction primarily. Not usually found on most cruising boats

6 - Coremat. This thin (about 2-3mm) stuff acts like a sponge and absorbs resin to form a thin core for small parts. Useful when stiffness is the main governing requirement for a part. I used this to make Dorade boxes when I wanted to keep the wall thickness thinner than a typical 6mm core would provide.

7 - Stirring sticks. Get your kids to save their popsicle sticks. Rinse them first. Then stir for 2 minutes, timed with a watch. It's longer than you think and boring too. Scrape the sides of your mixing container well.  Nothing sucks more than having your epoxy not cure. Do not use your wife's wooden spoon and try to wipe off afterward. She will notice.

8 - Mixing containers. Save those yogurt containers too. Rinse well. Nothing stops a nice epoxy from curing than a lump of fermented milk product. When the resin has hardened, pop out carefully and re-use a few more times if you are lucky

9 - protect your hands. Epoxy is a skin sensitiser and you will get allergic reactions if you keep letting it get it on your hands. Or thigh. Or in your hair. 

(White vinegar will get uncured epoxy off your skin and is much nicer than using acetone. Wash with soap and water afterward. Epoxy in hair? Let cure and reach for the scissors)

10 - Digital Scale, accurate to +/- 1 gram. Many epoxy mixing errors are caused by measurement errors in measuring volume.  Almost all epoxy suppliers will provide mix ratios by weight and volume.  The ampreg 22 resin I use is a 100:28 ratio.  For every 100 grams of resin you add 28 grams of hardener.  If you pour in 172 grams of resin you need 172 x 0.28 grams of hardener. The math is not hard!  I can reliably measure down to about 30 grams of mixed epoxy. That's about the weight of a small chocolate bar. 

I really should cover the scale with some cellophane wrap too but I pour carefully instead.  I also weigh my cloth before starting so I know about how much resin to mix.

If you're using those little mini pumps watch out for when they 'burp' and give you a little air bubble as you're mixing. Or the pump gets partly clogged at the end of its travel by the plunger mechanism. It's all too easy to get it wrong. Some people even forget to keep count of how many pumps they did.

11 - A Calculator dedicated to my sticky fingers.

12 - I almost always use plastic squeegees for spreading resin onto cloth. The only place it won't work well is on vertical surfaces. I will wet out the cloth on a horizontal piece of plastic drop cloth and then stick it the to the vertical surface. If you want a good cloth / resin ratio, squeegee hard until the cloth looks almost dry.  Brushes soak up more resin and are expensive.

You can more easily pop off dried resin from squeegees by leaving a thick layer of resin on it. Sand the working edge with fine sandpaper to you don't catch fiberglass cloth with little burrs when re-using squeegees

13 - Very well used Olfa rotary fabric cutter. Much nicer than scissors for cutting large quantities of cloth. Use on a hard backing surface.

14 - syringes are used to squirt epoxy into holes in the deck or other tight crevices

15 - packing tape - one of the best mold releases known to mankind. Really effective on flat or mildly curved parts. Use the brown stuff so you can see it better on your mold surface. Forget wax paper or cellophane. Wax paper doesn't have enough wax to reliably release, and cellophane is too flimsy.

 oops - forgot to put a number on the item above 5.  Call it 16

16 - peel ply.  Peel ply is a fancy name for a lightweight nylon fabric you apply to a wet laminate top surface. Squeegee it down firmly onto the laminate. When the glass is hard, peel it off the laminate. You will get a much nicer surface with no stray glass shards or hairs and suitable for further bonding. Once you try it you will never stop using it.

Buy your peel ply at a fabric store. Look in the discount bins where nobody wanted that neon green ripstop nylon for some reason.

NOT SHOWN - a decent supply of biaxial fabric and Corecell foam core is stored in a locker for all those projects that are just itching to ... that reminds me of one other very important item: 

BABY POWDER.  If you have to grind or sand a lot of fiberglass, very liberally dust your exposed skin with the stuff. It seems reduce the itchies significantly. That, and a cold shower immediately afterward.

Here's a recent project. This is a bracket for a swing out seat at Maia's school desk. The old bracket was a piece of bent aluminum pipe with a bloody big bolt for the seat to pivot on. It eventually bent when 2 kids sat on the seat.  The new bracket is lighter and structurally cleverer using thin carbon tubes. It supports my weight.

How you make it: Used carbon fiber windsurfing mast tubes are the base material. The tubes are roughly notched to fit, joined with epoxy putty fillets, and allowed to harden.

Thin strips of wet out carbon uni fiber is wrapped around the joints. Peel ply is used to cover the laminate. Then electrical tape (used backwards i.e. sticky side out) is used to squeeze the joint and consolidate the laminate. The outboard end of the bracket has a s.s. pin in place for the seat and this technique is being used to tape the pin in place. Note the drips of excess epoxy onto the plywood scrap below.

- Evan

June 11, 2014

We Made Vanity Fair

I'm used to writing about other people and, at times, ourselves but being the person who is written about is a new experience. Several weeks ago I had a wonderful conversation with Greta Privitera a writer from Vanity Fair Italy. While writers and reporters in the US were up in arms over the rescue of Rebel Heart (I was interviewed for both radio and TV and felt like I needed to defend our lifestyle) Greta was simply curious about how we made our dream come true.
Six-year-old sailor

It was a lovely and refreshing conversation. I'm not sure if it was cultural--but her concern wasn't for Maia's safety, but for Maia's own dreams and happiness. How do we know boating is still the right thing for her as she grows and changes?
life aboard

I don't speak Italian and google translate is a very imperfect thing, but the parts of the story that I could read made this whole cruising thing sound incredibly cool. I sort of love Italian us:

"Quando Diane parla della sua scelta di vita, l’opinione pubblica si spacca in due: «Che famiglia fortunata» e «Ma siete pazzi?».
Diane Selkirk e suo marito, due canadesi di Vancouver, sono quel tipo di persone che come tutti avevano un sogno, ma che come quasi nessuno hanno scelto di seguirlo.
Sognavano di prendere una barca e girare il mondo, e l’hanno fatto: Messico, Costa Rica e Nicaragua, Salvador, Australia, Polinesia Francese, Stati Uniti.
Hanno solcato gli oceani in lungo e in largo, prima come coppia e poi come trio, con Maya, la loro bambina. Questa scelta di vita, e quella di altre 10 mila famiglie che in questo momento si trovano per mare, fa discutere l'opinione pubblica."

pin the sailboat on the voyage--dreams of a circumnavigation

Nineteen days without seeing land. "You would think" what a bore. " Not so. Every evening, on our catamaran, is a party. We cook special things, dance under the light of the stars and read together. In our travels we have seen thousands of whales, dolphins, sharks. We made all kinds of adventures and met people from every continent. We feel as if we are living in a 5 lives. It's a priceless feeling. "

June 10, 2014

More Maintenance - Exhaust Elbows

Our engine is a Yanmar 3GM30F. The exhaust mixing elbow is a known wear item. It carbons up, and rusts out from the inside. While carbon can be scraped out, the internal rusting can't be fixed. It should be replaced regularly - especially if you are heading out for areas of the world where parts are harder to get.  Our engine is about 15 years old. The previous owner put about 550 hours on it over 10 years, and we now have a total of 2200 hours on the engine.  In diesel terms, it's fairly young - and I wouldn't be surprised if the exhaust mixing elbow is original.  I'm slowly learning that preventative maintenance is easier than fixing things in exotic locations.

Recently the engine's exhaust has been smoking and the engine has showing some signs of overheating.

Have a look at the exhaust passage of the old elbow and compare it with the size of passage shown in the new mixing elbow.  Note the old elbow opening is probably 1/3 the area of the new one.  Poor engine couldn't breathe...

June 9, 2014

Maintenance Thoughts

Hose clamps are evil. They are trying to sink your boat or dash it on the rocks. Don't believe me?

Exhibit #1:
 See that hose clamp on the bottom of the hull, about halfway between my foot and the shaft seal? It's a broken hose clamp. Its purpose is to stop the shaft seal collar from sliding forward, if it's set screws ever loosen off. Which they do - on our maiden voyage with the new engine we had a minor sinking emergency when that very thing happened.

So the hose clamp is just a backup in case the set screws fail. But it has fractured, no doubt due to very small amounts of salt water mist that the shaft seal lets through. A new one is in place, just to the left of the shaft collar.

Exhibit #2
 The hose clamp on the left is the one from the picture above. The one on the right is from the engine's fuel line. I was changing out our electric fuel pump (useful for priming the system after you change the fuel filter or in case the diesel lift pump fails). It came apart in my hand.  It looked fine. Had it failed in use, the engine would have stopped running due to air in the fuel line.

A tale of two masthead lights. Masthead lights (aka steaming lights) don't sit on the masthead, they are located on the front of your mast and indicate you are under power. Stupid name but that's the COLREGS for you.

 This is a Perko light. It is heavy, made of cast zinc and the design has not changed in at least 30 years. It is stupid. How do you change the bulb, dangling 20 or 40' in the air on the front of the mast?

1.  Remove the two machine screws holding the fixture to the mast

2. Flip over and remove four teeny tiny screws on the back.

3. The front lens then comes apart, into three loose pieces.  Which you have to hold into place after removing the bulb and screw back into place.

4. In doing so, you yank the semi-corroded wires from their nuts.  No problem, just loosen the nuts and re-attach the wires.  However the nut also holds the bulb holder inside the fixture. So when you loosen the nut, the bulb falls inside the fixture.  Go back to step 3.  Design like this has no place on our boat. So I yanked the evil thing off and replaced it with this:

The new light is a new Aquasignal.  It has 1 screw to remove the lens and get at the bulb. Older versions had two.  Somebody at Aquasignal knows lights.