Navigation | Sailing Blog - Technical Hints and Tips - Sailing Television

Summer Solstice in a Half-Tropical Island



Those who have been to the Southern Exumas in the Bahamas know it’s a special place. Warm “tropical” climate, blue waters, lovely white sand and friendly people. But on the Summer Solstice these islands are even more special as they highlight the fact we are “not quite” in the tropics.

Not quite??

June 21 2014 is the Summer Solstice - the point where the sun stops moving north and starts moving back south again. (The word solstice is from the Latin for "sun-stopping"). This northern-most point is marked by a line of latitude known as the Tropic of Cancer and passes right through the south end of Great Exuma. That's just 2-3 miles from where we are anchored in Exuma Harbour today.

So are we in the tropics? Well, literally, no we are not as we sit anchored off George Town. The Tropic of Cancer is just slightly south of here so most of Great Exuma is not in the tropics. But the southern tip of the island is. So it’s a half-tropical island. (The term semi-tropical refers to climate conditions rather than astronomical position.)

This anchorage at White Cay is just 1 mile south of the tropic. So if we anchored here we would see the sun very slightly north of us today at noon.

Cool!

FYI Here is a nice site with more technical information if you like.

White Cay41
Comments

How to Read the Colour of the Water



water colours5
How deep is the water in the picture above? Could you anchor here?

If you want to safely cruise and enjoy the Bahamas or other shallow tropical destinations it is important to learn to read the depth by the colour of the water.

This picture is taken near White Cay south of George Town in the Bahamas. The light turquoise makes it look like a shallow swimming pool, and you can see that the bottom is all white sand. The blue colour of the water means that the light is travelling through enough water to change the light from clear to this blue colour.


The pale blue above means a bit more than 2 meters (6.6 feet) of water for us to see that level of “blue-ness”. So you would need a shoal draft boat to go in here.

water colours11
Here you can see the shallow water in the foreground (and far background) is less than 1/2 meter deep by the very pale blue-ness and to the right of the photo behind Distant Shores II is dry sand, therefore yellow. We are anchored in 2.5 meters.

Using the water colour to judge depth takes a bit of practice, and needs good light but is well worth the effort!
water colours9
Keeping a close lookout using quality polarized sunglasses is important. If you are unsure if your glasses are polarized, you can tilt your head to see if the image changes. Looking at clouds in a blue sky you can see the sky get a darker blue. If you have an LCD display handy you can see if the image darkens when you tilt your head - then you have polarized glasses.
water colours7
Here is a view with high sun through normal lenses... and below of the same view with polarized glasses.
water colours6
In this view you can see the water is quite a bit deeper. It is actually 4 meters - 13 feet deep and you can see a few small isolated rocks or small coral patches on the bottom. The patches are also deep so it is safe to navigate over them and you don’t need to dodge each one. If rocks are closer to the surface you can see them as sharper and darker colours.
water colours3
Here is a shallow coral beachfront (in the Turks & Caicos of Provo). This is all a “no-go” area since the bottom is rocky reef. The water over the reef patches looks brown, and is less than 1 meter deep. Anytime the water has that brown look is too shallow - even for a dinghy!

Below is an example of the water at 2 meters deep. We are approaching Hog Cay Cut in the Southern Exumas. Ahead you can see the cut as we leave the banks and approach George Town, Great Exuma. Note that a little further ahead you can see some slightly lighter colour water where it shallows to just 1.5 meters. Hog Cay cut is a tricky passage, and if you draw more than 1.5 meters is not recommended. There are spots with just 1 meter of water depth so most boats need to use a high or middle tide to get the extra water to make this passage safely. We are coming through on half tide and indeed find just 1.5 meters of water.
2 meters shallower ahead
Finally here is a nice shot of the anchorage in George Town off Stocking Island.
water colours10
The water is less than 1 meter deep in the shallow bank in the centre of the photo. The main anchorage is mainly 3-4 meters deep and you can see grassy patches where it might be a little shallower. Anchor in the sandy bits for good holding and to enjoy your shallow water paradise!
water colours12

For more information on shallow water piloting check out “Cruising the Bahamas”, a one-hour video available on DVD and download as well as in the Bahamas/Caribbean Gift Pack of Distant Shores DVDs. All good resources for planning your upcoming cruise.

You Might Also Like the following...
Shallow Water Piloting
Tuning the Rig
About the Southerly 49
Top 10 Canal Journeys
Comments

Shallow Water Piloting



Wardericka
Ahhh Bahamas. Could this be the most beautiful water in the world?? Tough to judge for the whole world, but for many people the Bahamas are the best! And for American and Canadian sailors on the East Coast the Bahamas are the achievable paradise.

But beautiful as they are, the same shallow seas (Bahamas means shallow seas in Spanish - baja mar) can be a concern for sailors new to the practice of shallow water piloting. And its not just for shoal draft sailboats! Even with our old non-shoal draft sailboat with 6 feet draft we used these techniques and enjoyed shallow draft cruising grounds.

Sheryl and I have cruised these islands many times over the past 25 years and spent altogether 14 months cruising the shallow seas of the Bahamas.

Navigation has changed here with the advent of pinpoint accurate GPS and plotters but most of the techniques for safely navigating here have not changed. There are few aids to navigation in the Bahamas. Sand bars shift and reef grow.

10 Navigation Tips for Successful Shallow Water Bahamas Piloting

  1. Time your passage. It is easiest to judge water depth with the sun over your shoulder. High sun works best - 930 or 10 until 3pm or 3:30 will be best. Try not to come straight into the sun especially when it is lower on the horizon. Do not navigate at night! Rising tide means you can get off again if you get stuck.Pipe-cut-4
  2. Do not rely exclusively on waypoints. Cruising Guides have waypoints and they are useful but these are not designed to be used alone. Keep a lookout as well even when running point to point. For new places or routes we haven’t tried, Sheryl and I will check both our charts plus cruising guides for additional information when planning a trip.
  3. Know your boat’s draft and tolerance to running aground. Can you afford to run aground? If you have exposed rudders or propellors be sure not to run aground. What is the calibrated offset of your depth sounder? Is the offset calibrated to the bottom of keel or to the water surface?Beached
  4. Wear polarized sunglasses. They cut the glare on the surface of the water so that you can see down into the water much better when wearing polarized glasses.paul-banks1
  5. Keep a good watch. Height helps - have a lookout standing on the cabin top or other high point. Do not look through windows or cockpit enclosures. Keep a sharp lookout. Post a lookout at the bow. Do not rely completely on Electronics. Binoculars1
  6. Slow down or stop when unsure.
  7. Learn to judge the depth by the water-colour. Deep sapphire blue to swimming pool blue to pale yellow is all sand. Deep green or gray-black will be deeper water of 3-5 meters over grass or reef. Brown water will be quite shallow water over reef or rock - less than 1 meters. Judge depth over sand from sandy colour (less than 0.5 meter - 2 feet) very pale light blue (1 meter) to deep blue. (I will go into this in more depth in my next Tech Blog, “How to Read the Colour of the Water” since it is an important skill for skippers to develop to ensure a safe and happy cruise.) .Turks-banks-3
  8. Practice with your depth sounder. Judge the depth ahead (for example, picking a shallower sandy patch) and confirm your estimation as you pass over this patch. Explore ahead in the dinghy and confirm depths with a lead-line.
  9. Try out a Lead-Line. On our first trip to the Bahamas in 1989 friends gave us a lead-line neatly designed for our boat (which drew 6 feet). It was a 20 foot piece of thin cord and had ribbons tied every 2 feet with a fishing sinker on the end. The ribbons at 2,4 & 6 feet were red indicating depths we couldn't go. 8,10 & 12 were yellow and 14,16 & 18 indicated we could easily anchor here. Great for scouting in the dinghy or for checking depth off the stern...
  10. Be careful in cloudy conditions. The small trade-wind clouds common to the (otherwise) perfect sailing day in the Bahamas can cast a shadow on the water that look just like a black reef patch. The clue is to carefully watch the bearing - if the bearing changes then it’s a cloud. If you are unsure, head around it. When you get closer it’s easier to see if it’s really a reef. Not all clouds pose a problem. Soft clouds or on a high-cloud dull day it is still relatively easy to judge water colour.

Here is a video on the first time we beached our Southerly 42 in the Bahamas


We love the Bahamas and enjoy the challenge of piloting in the amazing blue waters here. A little preparation and practice will allow you to safely navigate this wonderful cruising ground.shallows

Dreaming-White-Cay22buttona
Join our email list and get hints, technical articles and tips plus videos to help you achieve your cruising dreams.
  • FREE 1/2 hour video on cruising the Exuma Islands in the Bahamas
  • Technical Blog shows you how to deal with issues facing the cruising sailor
  • Destination information from some of the world's best cruising areas
  • Special discounts and promotions

Click Here to Sign up

Comments

Cruising Guides - Still relevant?

We have recently had a few emails asking how we plan where we will sail to on our next voyage. Everyone is becoming so used to looking everything up on the web, is it possible to just get our cruising info there too? Do we still need Cruising Guides? It got me thinking about our method of voyage planning.

Background Information


For years we have followed roughly the same method. We initially read about interesting cruising destinations in sailing publications or websites as well as talking to other experienced cruising sailors about the places they love to explore. Boat show seminars are another great resource. Then if a cruising destination holds a serious appeal to us, we buy a cruising guide or two about the area. We flip through them trying to get the flavour and basic information about the places. What season to visit? What are the hotspots? What did the author find most worthwhile to include photos on? What are the anchorages or harbours like? In many cases the author’s introduction is valuable. You are learning from someone who often has many decades of experience in these waters. Compare that to reading a blog... the blogger is reporting back on his first and likely only visit, and how things went for him. He may have got lucky, or unlucky with weather, he may have had boat problems and report mainly on how easy it was to get things repaired? All potentially useful, but not the definitive account. Although we read and reference websites and blogs for insights into the experiences our fellow sailors have had cruising in a place, we would never depend on them entirely as the only reference in addition to good charts.
cruising-guides-europe-uk-imray - 1

Harbour Entry Advice


Here is another time when we really like to have a cruising guide on hand. Entering a new harbour, planning a safe anchorage, the cruising guide is your local expert at your side. Looking at a chart is going to be necessary at the next step as you plan the actual route and when you are there navigating, but the cruising guide contains very useful hints and warnings to help you interpret the chart and cross-reference any discrepancies.

For instance, here in the British Virgin Islands where we’re currently cruising there are MANY bareboats and people who do not have local knowledge, or even any experience on the boat they’re sailing. A cruising guide is a GREAT idea and fun way to get into the spirit of the trip weeks before you even arrive. And when cruising here the guide is a great resource as you come in to a port for the first time. The sections on "Approach & Entry" to the harbours warns of off-lying danger and offers a safe conservative route in.

For example coming around to Gorda Sound here in the BVI there are a couple of options to enter the harbour. But the first convenient option south of Mosquito Island is really too shallow for most boats. "Cruising Guide to the Virgin Islands" (Nancy & Simon Scott) states...

"There are 3 entrances into the Sound but only one that is well marked. The western entrance via Anguilla Point is tricky and should only be used by those with local knowledge. Most bareboat companies place it off limits".

Sketch Charts


Cruising Guides also include sketch chart - simplified sketches showing the recommended routes, anchorages etc.. These are not at nearly the detail of the proper charts, but drawn with the author’s local knowledge. Here’s the entry to Gorda Sound from the "Cruising Guide to the Virgin Islands" .
Gorda Sound Guide
We have gone through this entrance many times and know it quite well. There is less than 5 feet of water on the route so we swing up our keel. Last week we were heading in and a charter catamaran was following us toward it. They probably thought we were deeper than them so they could safely follow us. In fact we draw less than 3 feet and they (a Leopard 47) draws 1.5 feet more than us! Luckily they thought better of it and veered off. Perhaps they were reading through their cruising guide and changed their mind?

The moral of the story? Cruising guides are still a good idea! Up-to-date charts are important! And don’t follow other boats especially if they are lifting keel boats!

Here is the wide shot on the Navionics chart. Notice there is a "Note - See Lower Zoom" near our passage...
Gorda WS
When you Zoom in the note recommends against it... and accurately shows the depths. Too shallow for the deeper cats!
Gorda CU
Comments

Season 2 - Equipment Roundup

Well it’s been a great sailing season! We have never been so far north! We sailed almost 4 thousand miles and had a chance to fine-tune the new boat! Here is a round-up of new gear that stood out from this season of sailing!

Feathering Prop - Autoprop - Last year I lamented the lack of a feathering or folding prop since I felt we lost too much speed with the big fixed 3-blade prop. So this year we changed to an Autoprop. What a difference! Getting rid of a fixed prop has to be the first thing to do to improve performance. It’s like towing around a bucket. Dollar for dollar it must be the best way to get more speed. The Autoprop automatically adjusts its pitch depending on speed through the water and seems to work quite well.

Downwind Pole - Selden Carbon Pole - We have always had a downwind pole and use it to pole out one of the headsails when sailing right downwind. We hadn’t got around to installing it when the boat was new so we added it this spring. It’s a carbon pole and even though it is quite large it is easy to lift with one hand! We used it 6-7 times this summer. Mostly it was in quite light air when we might otherwise have had to motor. Nice to have it back!

Anchor tackle - Rocna 33KG + 80 meters chain - Norway this summer meant some very deep anchorages. We anchored in 12-18 meters of water a few times. Yikes! It was great having long chain and knowing we would be fine. And as usual the Rocna set beautifully. It is a great all around anchor.

Autopilot Remote - Raymarine Smart Remote - This is a little wireless remote to control the autopilot. It also includes a repeater for all the basic data (speed, depth, wind, heading, VMG etc). On cold or rainy days it is nice to stand up under the dodger (sprayhood) and steer with the remote. Sheryl can take it up to the bow when we are anchoring and check the depth before she drops the hook.

Electronic Charts - Navionics Charts + Apps - Electronic charting has come a long way in a few years. The newest charts are amazingly accurate, and now include lots of other data. Aerial photos of harbours we are approaching are a very nice addition. All tide data is also included so when we sailed in the Brittany coast and the tide exceeded 8 meters we could quickly find a tide station to check where we stood. Much quicker and easier than using printed tide table. Plus I have to recommend the Navionics App!! We have this on our iPhone and it’s amazing. All chart data, plus tides for the British Isles is included in an app for around $20!! How could you NOT buy this. It works for iPhone and there is a HiRes version for iPad. It also comes for Android devices. It’s great for planning (and even serves as a back-up for our chartplotter.)
Comments

Navigating - Raymarine, iPod & iPad

Navigating safely has been getting better and easier. Recently we got an iPad with GPS and Navionics charts and I’m looking forward to trying it out on the upcoming cruise.

Last year’s cruise with the new boat we had two new instruments to make navigation easier. The Raymarine E90Wide plotters were great! We have one right at the helm in a pod, and the other up under the dodger (sprayhood) as we use that position at sea. These plotters are a hybrid using touch screen but also have buttons. I loved the buttons and used them most of the time but on rainiest days sometimes switched to the buttons. Often we found ourselves using both. Buttons are convenient for zooming, and then dragging the screen to a new position. Nice!


The plotter at the helm is often right in the sun and this highlights one of the biggest advantages in my mind about a proper marine MFD (multifunction display). The E90W is completely readable in even bright sun. Try that with your laptop! It is also dimmable right down to almost nothing for use at night. It won’t ruin your night vision but you can still see the screen. It it completely waterproof and ready for tough marine conditions like a rough day on the Kattegat as seen here...

As a fun test I got the Navionics App for my iPod last spring. So we have had a full season cruising and have got to recommend them! We got the Apps for UK/Holland and found it a great tool. It has the tides as well as the full charts for the area and I often found myself using the App to plan our departure times and course - especially in the trickier tides of the Channel Islands. The screen is too small for use with serious navigating but it still had one interesting use. Because it is so small and I always carry my iPod around, I often found myself using the charts when comparing notes with other cruisers. We might be meeting up on someones boat and discussing upcoming destinations. I could pull out my iPod and put on a recommended waypoint or anchorage. Very cool!!


Now we have an iPad I have added the Apps for it too (available in HD for the bigger screen). It will be fun to try this out on the next cruise! I am certain it will it will be a useful addition to our navigation equipment.
Comments

Equipment Roundup

Having the new boat has been a great opportunity to get that new gear I always thought would be a good idea. I thought I would do a round-up of the equipment now that we have had a year to try it out. So here goes... in no particular order

Electric heads - Tecma - they have been brilliant! No breakages and no servicing required yet. I had thoroughly disliked our Jabsco heads previously. They needed constant maintenance, required way too much pumping to operate and frequently seemed to malfunction. There had to be a better way and the Tecma electric head is perfect for us. I have ordered a spares kit for them (not cheap!) but it is well worth it. I know purists will suggest an electric toilet is somehow “not proper” but if all fails we always have a bucket...

Forced Air Heating System - Espar - Wonderful! Nothing beats coming down below to a toasty warm boat after a cold/wet sailing day. The Espar has just worked flawlessly. It does have a small and slightly bizarre control panel that does theoretically allow it to be turned on and off at preprogrammed intervals but we haven’t used that option. We just turn it on and set it for 1-3 hours as needed. Great!

Plotters - Raymarine’s new E90Wide X 2 units. These are the new touchscreen hybrids that have full control either with touch or buttons. The plotter is the heart of the boats navigation system and the E-wides are excellent. I really like the touch screen ability including a popup onscreen keyboard to name waypoints etc. These units also come with a huge number of built-in charts - another big savings over the old style. But adding the Navionics charts is great also since it gives you harbour info, tides and currents plus aerial shots of harbours if you don’t have a cruising guide. The picture above was shot leaving Amsterdam at night. The plotter up on deck working perfectly as usual. Bright enough to be easily read on the brightest day, it also goes right down for night use. With the radar and AIS overlaid we can see ships that might otherwise be hard to spot against the lights of the city.

Electric winch - Lewmar conversion - This was a lifesaver! We sailed a couple of months then added the electric winch so we can compare before/after. The 49 means everything is 20-30% bigger and raising the mainsail was a tough slog. On the 42 I pulled the main up to just 1 meter from the masthead then put it on the winch. With the bigger 49-footer the same effort means I can pull it with 4-5 meters left to go. So I have to winch the sail 4-5 times as far. The electric winch handles it easily. It also meant we had no trouble going up the mast. Sheryl can easily pull me up and that meant we could get more shots from the masthead!! Depending on your boat, an electric winch could make sense. Even just adding one as I did could change your sailing a lot.

LED Lighting - Imtra - A revelation! Finally LED lighting that works and lasts! We can now afford to turn on any lights we light. On the darker winter days we can run all the lights we want. Using perhaps 1/4 the power of the old lights. The lights are designed from the ground up as LED lights rather than adding replacement bulbs to conventional fixtures. This means they can build in a nice heat sink for the power circuits. I am sure they will last for many years giving us a cozy well lit boat!

...
This is just the start... now I am rolling I want to go through more tomorrow - anchor, engine etc...
Comments