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Sailboat vs Trawler Anchoring ..

Jeff Seigel, founder of ActiveCaptain, writes…

As we pulled into the anchorage north of the Lake Worth inlet this week, in our trawler Red Head, we found ourselves in a sea of sailboats. It made us realize some of the issues to think about when picking a spot for both sailboats and trawlers especially when both types of vessels are in the same area.

There are a couple of things that might not be obvious about anchoring but are critical to careful planning. First, the amount of rode you let out after making a scope decision includes the high water level and the height off the water where your anchor rode is attached to your boat.

Ignoring a situation where you're anchoring in very deep water, many cruisers pick about 5:1 scope for anchoring. 7:1 allows us to sleep better. 10:1 would be used if a bad storm were expected.

So if you decide to use 5:1 scope in 10 feet of water when there is an additional 3 feet of tide expected, and your anchor rode is attached to your boat 4 feet off the water surface, the amount of rode to let out should be:

                                         ((10 + 3) + 4) * 5 = 85 feet

The second thing that many people don't realize is that a bridle does not reduce the attach point of the rode to your boat unless the bridle line is attached to the boat at a point lower than where your chain exits the boat. It is most common that the hawse holes/cleats where the bridle attaches are at the same height as the anchor chain exit so in reality, a bridle does nothing to reduce the rode based on scope. This is often argued but it's true. When the wind picks up, your bridle will raise out of the water and form a straight line to the anchor – it has to. It's easy to prove with some string and a toy boat.

So here's the potential problem when sailboats and trawlers anchor together.

We all want to use similar scope, yet it's often the case that trawlers put out a lot more rode. It isn't because they're being selfish. It's because a trawler's rode attach point on the boat is generally at the bow which can often be 8 or more feet off the water.

Here's a real example:

  • A sailboat and a trawler are anchoring at low tide in 6 feet of water where a 3 foot tide is expected (the Lake Worth anchorage).
  • Both boats will put out 7:1 scope because the strong winds are expected
  • The sailboat's rode attach point is 4 feet off the water at the bow.
  • The trawler’s rode attach point is 10 feet off the water at the bow chain lock.
  • Sailboat rode: ((6 + 3) + 4) * 7 = 91 feet
  • Trawler rode: ((6 + 3) + 10) * 7 = 133 feet

In reality, we put out 125 feet of rode because I did the calculation in my head. I believe the sailboat who anchored in front of us put out 75 feet of rode.

In the middle of the night, there was a major wind change with a big storm. As we swung around, we'd now be in front of the sailboat. And it would feel like we were 50 feet closer to the sailboat since we had

50 feet more rode out than they had. We'd end up being a lot closer even though neither boat dragged an inch.

These are the things to take away from this:

  • If you're a sailboat, be very careful when anchoring in FRONT of a trawler with a high bow. Consider the difference between your bow heights times the scope to estimate the distance they'll move closer to you when the wind shifts. So in the example above, you should move an additional (10 – 4) * 7 = 42 feet in front of the trawler than you expect.
  • If you're a trawler, you have a similar responsibility to consider your extra rode distance especially if you're anchoring BEHIND a sailboat with a big wind change expected. You will move closer and you must account for that before you pick your spot using similar bow height estimates.

Trawler owners can correct a lot of the extra rode needed by having a bow eye placed near the water line and having the anchor attach there.

That will be the subject of another newsletter….

Also, don’t forget to use and understand my app for your tablet/phone – DragQueen..

 

ActiveCaptain

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Headsets – The Next Generation…

Jeff Seigel, founder of ActiveCaptain, writes…

For years, we've talked about the advantages of cruising couples using headsets for communications. There is no substitute. While hand signals may work in many conditions, we've found good communications is most needed when both hands are busy. And nothing compares to the ability to calmly and reliably talk between crew members while docking, anchoring, and during other maneuvers. In stressful situations, great communications removes much of the stress.

We bought our first headsets, the original toy models, in 2003. They became so important, we bought a second set in case there were problems.

They used the AM radio band and eventually started to pick up interference with the new electronics we were putting onboard.

About 5 years ago, a new generation appeared, characterized by the Eartec Simultalk 24G Multi-Station Wireless System. These used more professional audio equipment and radio bands to deliver a better solution. When we delivered Red Head from New York to Deltaville, those Eartec's were the first things we put in the pilothouse.

Five years in consumer electronics is many lifetimes. And today there is another, newer generation of headsets for boating. The two new models available are the Sena SPH10 and the Eartec UltraLITE. 3 months ago we were offered a set of each model for evaluation. We had one rule – if we evaluated them, everyone agreed we would release our honest findings in writing.

Both models use Bluetooth which means they can also connect to phones and other devices. We never used them for that – we only used them for docking, anchoring, and general communications (running wires, etc).

Bluetooth requires a pairing process to connect the devices together.

This provides a level of security so no one can overhear your communications. For both products, we found the pairing process to be annoying. The combination of pressing, holding, tapping, and standing by seems ridiculous. The instructions were not great for either product. We found the best way to get them to pair was to find YouTube videos and watch the procedure carefully.

Once they are paired, they remember their connection making real use much easier. Again, if you have procedural problems, look to YouTube for help.

So what did we find? We used both sets for all operations in different weather conditions. They are surprisingly similar and we can say that either model will do a great job. This new generation doesn't require a pack – everything is in the headset itself. That makes it a lot nicer than the previous generation. We do have our favorite and we'll explain it through a list of plusses and minuses for each product:

Sena SPH10:

+ They are small and comfortable although comfort is a personal thing A
+ USB cable charges each headset They have longer talk time
– It is difficult to talk in heavy wind conditions
– They are more expensive (especially this week)

Eartec UltraLITE:

+ They work amazingly well in heavy wind
– They block more outside sound on one ear – don't get the two ear model
– Batteries have to be removed for charging
+ A single battery charger charges the batteries for both headsets

Either device will work well and both are excellent for docking and undocking situations. But the Eartec's were significantly better when deploying and retrieving the anchor in the wind. And for whatever reason, we seem to frequently anchor in windy conditions. To make the comparison fair, during the anchoring tests in the wind, we switched headsets back and forth. Perhaps the Sena's need a windscreen or some type of mic that is less sensitive to wind. But there is a difference and for us, we're sticking with the Eartec's.

If you're a couple in a cruising boat and still believe that hand signals are all you need, borrow a set of headsets from someone and give it a try. Once you do, you'll never want to give them up.

ActiveCaptain

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Offbeat Charters from SuperYachtWorld

This is another great Google Map from Louise Busby..and in her own words “An increasing number of superyacht owners and charter operators are relocating their vessels to far-flung corners of the globe to entice the growing band of charter guests tired of cruising round the same old watering holes. We’ve searched the planet for the pick of these yachts and the experiences they offer, from sun bathing with iguanas in the Galapagos to snorkelling with elephants off those gems of the Indian Ocean. “….Great job Louise !


View Larger Map

..although sailors and power boaters dont always get along:-) – I have to take my hat off to Louise who is web editor of the Broom Users Club and who has also the author of Inland Waterways of the Netherlands.

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Rocna Anchors New Knowledgebase

Rocna KnowledgebaseRocna Anchors has released a comprehensive online collection of information on the topic of anchors, anchoring accessories, and the science of anchoring.

The Rocna Knowledge Base is a comprehensive, indexed and searchable digital encyclopedia covering anchors and anchoring.

The new website includes a section specific to anchors, including a collection of Rocna installation case studies, and guidelines for designing and building the ideal bow roller. Analyses of independent testing, explanations of anchor classification/certification, advice on sizing anchors and much more is also available online.

Content is not restricted to anchors; major sections focus on the rest of the anchoring system – chain, rope, connectors (shackles and swivels), windlasses, etc. Optimising rode make-up, best practice anchoring techniques, multiple anchor rigs, tandem anchoring and optimising the scope and catenary of the rode for best anchor performance are just a few of the topics covered in-depth.

You may also like to check out my previous postings on the subject of anchoring.

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Mobiletide

handsetsmallMobiletide is a Java program designed to run on your phone without need to connect to the phone network (GSM) or the internet (GPRS) – just as well !

It has a database of worldwide locations and can display a tidal curve for any location without you having to reference tide tables or do any standard port calculations.

The makers list a broad range of mobile phones that are supported, but basically any phone that runs a Symbian or Windows Mobile should suffice since they will then support internet connections and also Java software.

Mobiletide is synchronised to the moon’s daily cycle of 24hrs 50mins and 28 seconds. On average across a Lunar day (month) this is how much the tide moves on by each day. Working to an average tidal progression means that Mobiletide will remain accurate over a longer period of time, so in 5 days, 5 months or 5 years mobiletide will still be showing the correct tide. It does mean that throughout a month Mobiletide will fluctuate in and out slightly, however it will remain within 0-30mins for the majority of the time.

There are other influences on sea levels that affect exact tide times and these should be taken into account e.g. Strong on / off shore winds; Changing volume of river flows; Atmospheric pressure

Due to the variable nature of tides mobiletide is only intended as a guide to tide times. If you do have internet connection however, then the makers claim that Mobiletide has direct links to the most respected swell, wind and weather WAP sites around the world, providing the whole detailed picture.

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