Old Town Canoe

During Old Towne Otter Kayaks recent survey on a large steel yacht, the client elected to do the sea trial himself East Coast Kayak Fishing my presence was not required. I joined the ship at the ship lift ready for the lift and subsequent underwater inspection. Whilst waiting, I enquired how the sea trial had gone. Great said my client, except we had a bit of a fright when one of the rigging bottlescrews snapped To say my hair stood on end was somewhat of an understatement. What happened? What did you do? says I, Oh well, we had a spare on board and fitted another one onno sweat!

As you can imagine my attention was well and truly fixed upon the rest of these fittings during the subsequent inspection, especially when the client produced the broken bottlescrew for me to look at. The event was a common one, not at all unusual. It was a stainless steel bottlescrew with a Norseman screw down fitting to hold the stainless wire shroud. The exterior finish was rough and no load or stress numbers had been stamped or forged into the body of the screw. It was, in fact, a hybrid make of no known origin and the story became clearer as it unfolded.

The owner, a diligent young guy said, Weve been cruising for three to four years and as always money was a bit tight. We came across this great little place in Indonesia where these bottlescrews were so cheap we bought enough spares to replace the lot! Say no more. A year later, under a blue sky and a windless day just outside the Southport entrance on a sea trial, in almost idyllic conditions they changed tack and.bang. How differently this could have turned out.

The happy ending to this tale brings forth a subject that is generally unspoken of in daylight hours. STRESS CORROSION. We are all very aware of the normal day to day corrosion that occurs on board when seawater mixes with differing materials but stress corrosion is a different animal altogether and the results tend to be a little more catastrophic as the parts under stress tend to be quite important and are more often than not something to do with the safety and security of the boat.

HOW DOES STRESS CORROSION HAPPEN?
Well, the sad fact of it is that how stress corrosion actually happens is not fully understood. What we do know is that the metal goes without warning and often without any outward signs. It is also confined to high strength metals and the softer stuff such as gunmetal, silicon bronze and mild steel is unaffected as a general rule. It is worth a mention that aluminium rivets (N6 grade) are subject to stress corrosion and can lose their heads under certain conditions.

WHAT ARE THESE CONDITIONS?
The clue here is the word stress. The metal in question must be under tension and the temperature is usually high (about 150F, 65.5cever touched a bottlescrew left soaking up the sun on a hot day?). Finally, the metal must be regularly dosed in seawater whilst under load and ..bingo! The perfect conditions apply.

Locked in stresses during manufacture also count and injection pipes where temps are high (i.e. exhausts and elbows) are at risk.

However, back to the rigging.imagine the scenario. A badly designed bottlescrew (lots about) that has high inbuilt stresses, not 316 stainless but an unknown grade, rough surfaces and tensioned to the max for the stays and off you go, sailing in hot and salty conditions. Actually, even if you just leave the boat at its mooring those sinister forces will be at work. The wind in the rig produces a resonance that causes vibrations that can actually be heard and felt. The boat rolling produces alternating stresses. A yacht can roll in three seconds, one way, then the other. The rig keel bolts and rudder is loaded up then the load is applied the opposite way. Over thirty thousand times a day, one million cycles in thirty three days. How long has your yacht been rolling on its mooring?

Engines cause vibration and stress. Pipes, lines and anywhere that doesnt have rubber hoses that interconnect with rigid pipes are prone to stress and the subsequent cracking.

WHAT CAN WE DO?
Sensible precautions are the simple answer. Check all rigging screws have a traceable origin. Specifications when buying are important. Make sure load maximums are stamped onto components that are subject to stresses. Clean salt away on a regular basis from exhausts, engines and rig with fresh water and regularly check all rigging and change the lot after ten years use. Remember, mooring time counts, inducing fatigue cycles that will weaken rigging. Never fit high tensile bolts to keels or anywhere where the heat and chlorine (salt water) will abound. DO NOT over tighten these bolts at all!

Remember, stress corrosion starts with the tiniest cracks and often the component shears without warning because the cracks are too small. I have had people laugh at me when I produce my jewellers magnifying glass to look at rigging.but they soon stop when I show them the tiny hairline cracks I have found.

It is no laughing matter when thirty grands worth of rig crashes down onto someones head during a weekend away. Play it safe, do the job properly and then you can laughall the way to the bank.

If you liked this article and would like to have Terry Buddell write something similar for your magazine or would like to read more of the same contact dolphinboatplans or go to ezinearticles

Terry Buddell is a freelance journalist and a Marine surveyor, boat designer and Abel Tasman Kayak He lives on board his yacht The Nicky J Miller' that he built himself in The Gold Coast Australia and has sailed his yacht up the East Coast to the beautiful Whitsunday Islands. He is currently resident in Gladstone Queensland where he is building another boat for his collection! Terry can be contacted on :arcus1 bigpond arcus1 bigpond or dolphinboatplans dolphinboatplans

You've seen them a hundred times -- partially finished hulls resting on supports in the back yard of an ambitious sailor building his own boat. Sometimes, Yamaha Boats takes years and you wonder if they ever actually do any work on the vessel. The answer is yes and no. Boat building requires a lot of preplanning before actually beginning this task. Those yards that seem to have an unfinished craft up on stilts for years generally have an owner who either didn't really know what type of sailing he planned on doing Surf Kayak he was very short on money and could only get involved in boat building as funds became available. Questions you should ask before you begin would be what type of sailing do you want to do? Day sailing? Overnight cruising? How many of you will be using the boat at the same time? What can you afford?

Day sailing requires mostly getting the idea to build a boat, and then finding the right plans. You don't have to worry about long hours at the helm, or inclement weather. You can pick and choose when to be on the water and when to follow the ducks, and get out of the water. Any form of long-term cruising, however, means buckling down to the specifics and trying to think of every possible need before you get the plans to boat building. Overnight cruising for more than a few days with 2, 3, and 4 people on board would need a boat of at least 30 feet in length for comfort and safety.

Your next, very important, consideration is just how much money you have to spend on boat building. Staying between 30 and 40 feet keeps you roughly in the same ball park as far as buying supplies and outfitting your choice. If your eyes are bigger than your pocketbook and you decide you want something above 40 feet, this could easily turn into a twenty-year project, unless you are heir to a windfall.

Once you've determined the size of the boat you wish to build, think of the use. If you want speed, you'll want a long and skinny hull design. Taking the family for long cruises, you'll want comfort, stability, and maneuverability, which means a shorter, fatter, slower hull design. Both boat building designs should move through the water with the least resistance and best stability at all points of sail. After that decision, you can focus on the choices of keel, rigging and interior floor plan. You can play with the interior throughout the building process but not with the keel.

A full-length keel will give you the best ride in a 30' to 40' ocean-going vessel. For those boats 40 feet and above, try a modified keel for a little more boat speed without much loss in stability. In boat building, accept that most all other types of keels have a place on day sailors or racing hulls with a few exceptions. While not yet as popular in the United States, a double keel bottom is very stable and with the shorter draft, you can visit more interesting nooks and crannies within around your anchorage. Rigging is a matter of choice and you can find out what you like best by renting any number of sailboats throughout your boat building period. If you are still unsure, visit your local boating supply store and locate some designers who will be more than happy to help you. Knowing what you want to do, where you want to sail, and how much just another foot or two can cost you when you are building your boat, will be a clue to how long your own boat's berthing process will take.

For more information on boats, boating and other related topics, visit Travel With Vision at travelwithvision.org/travel-articles-general-2 Kayak Expedition