eOceanic

Making sight tubes easier to read

What is the issue?

Some older boats are fitted with transparent tubes, called sight glasses, to gauge the level of fuel or water stowed in a tank. These are by far the best systems to accurately assess the contents of a container but they have one critical downfall, sight tubes can be very difficult to read.

Mounted near to tanks they tend to be situated in awkward places that are as often as not subject to poor lighting. Also, as in the case of water which is almost transparent, they are very difficult to see.

Why address this?

Keeping track of fuel and water availability is essential when running and provisioning a vessel. A good sight tube system is perhaps the most reliable indicator if it can be used.

Sail with the Instincts of a Local Pro

Navigation apps only get you from A to B, leaving you guessing about the "where," the "why," and the "how." eOceanic isn't another "nav app." It's the Intelligence Uplift that enhances the tools you already use, powering up both your capabilities and understanding.

Once activated on your device, it doesn't just display data, it brings it to life with real-time situational awareness, giving you a "digital sixth sense" for the coastline.

Go beyond navigation to truly know the coast and everything it offers.

Sail Stress-Free: Make boat handling easier with a helpful assistant and avoid "hidden" hazards with an extra set of eyes on watch for dangers along the coast.
Discover More: Most sailors only experience a small fraction of a coastline's rewards. We unlock the "hidden gems" and local resources that create unforgettable experiences for you, your family, and your friends.
Engage Ashore: We don't stop at the waterline; we bring you in to fully experience the best of the world waiting for you ashore.

The power of knowing. Autonomy, agency, agility and the joy of roaming free.

How to address this?

Use the refracting property of liquids to make the fluid levels highly visible as presented.

Sight glass with diagonal lines
Drawing: Tony Gibson

A series of diagonal lines behind a sight tube will be refracted to the horizontal behind the fluid, marking the fluid level highly conspicuous.

Sight glass using the refracting property
Photo: Elsie esq. Les Chatfield via CC BY 2.0

Most yachts these days use sophisticated float switches instead of sight glasses. But they have to be calibrated correctly and cannot be totally relied upon until that is done. However, I got myself into a terrible mess on spring tides in the crowded Beaulieu River trying to figure out why my engine was running rough and cutting out when my gauge said I had somewhere between ¼ and a ⅓ of a tank of fuel remaining i.e. it was calibrated incorrectly. A sight glass may be just a plastic or glass tube connected to the bottom of the tank at one end and the top of the tank at the other, but it cannot be calibrated wrong. The level of liquid in the sight glass will be the same as the level of liquid in the tank of course, after making allowances for the shape of the tank.

With thanks to:

Michael Harpur, Yacht Obsession.

A photograph is worth a thousand words. We are always looking for bright sunny photographs that illustrate this experience. If you have some images that we could use please upload them here. All we need to know is how you would like to be credited for your work and a brief description of the image if it is not readily apparent. If you would like us to add a hyperlink from the image that goes back to your site please include the desired link and we will be delighted to that for you.

Add your review or comment:

Please log in to leave a review of this tip.

eOceanic makes no guarantee of the validity of this information, you must read our legal page. However, we ask you to help us increase accuracy. If you spot an inaccuracy or an omission on this page please contact us and we will be delighted to rectify it. Don't forget to help us by sharing your own experience.