Porthole Bungs Buying Guide

Aqua Narrowboat Furnishing specialise in boat porthole bungs. We are experts in designing marine soft furnishings and therefore have developed a range of technical printed fabric that is ideal in a marine environment.

How to measure your porthole window?

To ensure that we make your porthole bungs accurately, we need to insure all of our customers are measuring heir portholes the same and correctly. For a standard porthole bung with no cut out, the only measurement needed is the diameter, this is the distance (in cm) between the top and the bottom of the porthole on the inside of the trim. As seen below:

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How to measure cut outs needed due to porthole window brackets?

Cut out in the bungs are made in specific places to allow for the bracket of the window to protrude out whilst keeping the bung flat in the porthole. For this we need you to imagine there is a straight line running through your porthole from the top to the bottom. As the image shows (Blue Line), we need the measurement from the top to the parallel to the highest part of the bracket. We also need the width and the depth of the cute out (red and green line respectively on the image) in cm.

Please read these instructions carefully for measuring your porthole bungs, and caring for them:

Tips for Measuring

  • Porthole bungs will be made to fit inside a window recess
  • Always use a metal tape measure as cloth or plastic may stretch
  • Double check all measurements
  • Measurements must be in centimetres (cms)
  • Look at any brackets or wood features that will obstruct the blinds. Many boats have these at the top or either side of the window frames. If it is a top bracket, only one cut out will be needed, if there is are brackets either side, you will need 2 cut outs in your bung.
  • Make sure the depth of your window is 5cm, Let us know if your window is NOT deep enough for the bung.

Porthole Bung Sizes:

Small: 30- 40cm

Medium: 40-50cm

Large: 50-60cm

Manufactured: In the UK

Safety: All porthole bungs are made with a firm inner foam, a front fabric of your choice to match your interior, and black vinyl as the back fabric which is waterproof & wipeable. All fabrics and inner foam are fire retardant meeting British Safety Standards.


Please take great care with your boat porthole bungs. Whilst our fabric collection has been chosen for it’s durability, stain and soil resistance it will still be subject to wear, tear and damage if tugged and pulled too harshly. We recommend that you wipe clean & only use indoors