UBUC owns two 4.7m Zodiac inflatables each powered by a 40hp Tohatsu engine. The engines were bought with a grant from the Alumni Foundation.

Instructions on how to assemble the boats – Zodiac Mark III Construction


Our boats are powered by Ruby and Millie, two 40HP Tohatsu two-stroke engines which the club was able to buy in 2007 with a grant from the Alumni foundation.


The engines run on a 50:1 petrol:oil mix. It is very important that the engines are never run on unoiled petrol; this would quickly kill the engine. Also, only marine grade two stroke oil (TCW3) should be used, not the stuff for lawnmowers. Outboard engines run cooler than lawn mower engines and need to run at low revs for extended periods without burned oil fouling the spark plugs.

In theory oiled fuel can be identified by its darker colour and oily feel; normal petrol has very little colour and feels dry on your fingers. In practice this distinction is often difficult. If there is any doubt whether or not the fuel has been oiled don’t use it. You can always add more oil, too much oil won’t really harm the engine but too little is a bad thing.

On a trip it is best to nominate one person to be in charge of oiling the fuel. That person should, at the end of each day as the boats are being packed up, decant the boat fuel from half empty fuel cans into another to end up with some almost full and some empty cans. Then immediately add 500ml of oil to the empty cans. That way they cannot end up full and unoiled. It is best to only take empty cans to the petrol station; topping up half full cans requires remembering how much fuel was added and then working out how much extra oil to add (too much scope for error).

After a trip there is normally oiled fuel left over. If not used soon (within a month) it will quickly turn to varnish and if used will gum up the engine.

Attaching to the Boat

The engine needs to be placed in the centre of the transom and the bolts tightened. After the boat is launched and the engine no longer rests on the ground its weight will shift; check that the bolts are still tight. The chain on the transom is passed through both shackles at the front of the engine and the carabiner clipped on to the chain. This chain will stop us losing the engine if it falls off the transom. It is tempting to keep the chain as short as possible but it is better to keep it long; if the engine falls off we want it to fall far enough away from the bottom of the boat that the propellar doesn’t rip through the keel. The fuel line needs to be connected to the engine and to the fuel can.

Starting the Engine

Open the valve on the fuel can. Squeeze the bulb on the fuel line to pump fuel into the engine until it is firm. If starting from cold pull out the choke. Check that the engine is in neutral. Check that the kill cord is in place. Turn the throttle to the start position. Gently pull the starting cord out enough to take up the few inches of slack. You now need a long smooth pull on the starting cord to start the engine. Once it starts turn the throttle down and check the tell-tale; if there’s no water or just a dribble coming from the tell-tale turn the engine off straight away. Remember to push the choke back in.


Ruby and Millie have slightly different propellers; Millie has a larger prop with lower pitch. Effectively Millie is in a lower gear than Ruby and this affects their relative performance, and not as you would expect! Ruby, being in a higher gear, should have a faster top speed than Millie, and this would be true if the boats were only lightly loaded. However, if the boats are heavy, the more powerful Millie can get on to the plane with greater ease and

Repairs at Sea

Each boat has a tool kit to allow some minor repairs at sea, but working on an engine in anything but the calmest seas is a challenge. You don’t want to attempt anything but the most simple tasks like tightening something that is obviously loose. We carry basic tools and a spare kill cord, fuel line, pull cord, spark plugs and plenty of cable ties!


As well as the boats and engines we have cool electronics to help us find dive sites and keep us safe.


We have one fixed GMDSS radio and three handheld VHF radios. You need a licence to operate these radios except in an emergency. Have a look at the mayday procedure page for what to do.


We have a GMDSS VHF radio built into one of the boat poles. This radio supports Digital Selective Calling so at the touch of a button we can send a distress message that will be picked up and recorded by all vessels and shore stations in range telling them where we are. If anything happens to put the boat or divers in imminent danger hold down the red distress button and help will be on its way.

The antenna for this radio MUST be attached BEFORE you turn on the radio (and also the radio isn’t much good if you forget to attach the antenna!). The radio is attached to the GPS to get a constant update on its position; if you forget to turn on the GPS the radio will beep to remind you.

This radio runs off a battery which is housed in the yellow box on the side of the boat pole. The echo sounder runs off a similar but smaller battery which is in the same box. The connections for each battery are the same but are colour coded so that you don’t mix them up.The radio won’t transmit on high power if you attach it to the smaller battery.

Handheld Radios

We have three handheld VHF radios. These are a lot simpler to use than the big radio but have less range as they transmit with less power (5W vs 25W) and their aerials are lower. Close to shore, such as within Martin’s Haven, you won’t be able to reach the Coastguard; try again further out to see.

These radios are supposed to be waterproof but please leave them inside their waterproof cases. You should be able to press all the buttons with the radio in the case.


We have a Garmin Etrex H GPS which we use to find dive sites. It stays in the yellow box alongside the GMDSS radio. Remember to attach the data cable that connects to the radio and turn the GPS on to stop the radio beeping at you.

Echo Sounders

Each boat pole has a Garmin Fishfinder 90 echo sounder that tells us how deep the water is and helps us find wrecks and pinnacles. The transponder that sends out the sonar signal is the black probe at the bottom of the boat pole. The transponder is on a hinge, make sure that it’s pointing straight down or else the sea will seem very deep! The echo sounders are fairly reliable, but very occasionally they freeze and display a ‘blue screen of death’ type error. Disconnecting the echo sounder from the battery and reconnecting it solves the problem. Once one echo sounder displayed a ‘sonar error’ message; the problem turned out to be an old knackered battery, thankfully not the transponder or Christopher’s soldering!


The GMDSS radio and echo sounders run off 12V sealed lead acid batteries. There are two chargers to charge these up. These batteries should be charged up every night and not allowed to run flat. The connectors on the batteries are colour coded so that you connect the radio battery to the radio and not to the echo sounder. The radio draws more current and requires the larger battery. However, the batteries are interchangeable so that in an emergency you could run the radio off the echo sounder battery.

The GPS runs off AA batteries and there should be spares in the silver electronics case. Please take the batteries out when you pack the GPS away at the end of a trip; we killed our previous GPS by leaving wet batteries in it.


The fixed radio and echosunders are protected by fuses that are within the battery compartments. There are spare fuses taped inside the battery compartments and in the silver electronics case if they need to be replaced.

Mayday Procedure

Hopefuly you will never need to send this message or if you ever did there would be an experienced boat handler present who would know what to do. But should you ever need to send a mayday this is what to do. There is a copy of this page in each boat. These instructions are a simplified version of what to do in an emergency, you should do a VHF course and learn more about radio procedure.

Only send a Mayday message if a person or vessel is in grave and imminent danger. Sending hoax messages wastes rescuers time, may put others in danger and will get you into serious trouble.


Hold down the red distress button for five seconds. The radio will send a message giving details of where you are if the GPS is attached.

The radio should switch briefly to channel 70 and then switch to channel 16. If there is not a big 16 on the screen press the button labelled 16. Then take the microphone, hold down the big button on the top and send the following message, speaking clearly at dictation pace. Release the button when you’re done and wait for the Coastguard to reply.

Mayday, mayday, mayday.

This is dive boat Ubuc, Ubuc, Ubuc.

Mayday, dive boat Ubuc.

MMSI 235061135.

My position is… [longtitude and latitude are displayed on the radio].

[Nature of distress and assistance required].

There are [number] persons onboard.

[Any other important information].


Keep the message short, don’t go into unnecessary detail. If you don’t receive a reply send the message again.

Handheld Radio

Press the red 16 button, hold down the oval button on the left side labelled ‘PTT’ and send the following message, speaking clearly at dictation pace. Release the button when you’re done and wait for the Coastguard to reply.

Mayday, mayday, mayday.

This is dive boat Ubuc, Ubuc, Ubuc.

Mayday, dive boat Ubuc.

My position is… [where you are] [Nature of distress and assistance required].

There are [number] persons onboard.

[Any other important information].


Keep the message short, don’t go into unnecessary detail. If you don’t receive a reply send the message again.

A word to reassure you

Although we prepare for these emergencies they are very unlikely. Our boats are very sea worthy and difficult to sink; they’ll float even if full of water or with sections of the tubes punctured and deflated.

Boat Checklist

Before launching the boats check through the following list.


Check the tubes and keel are sufficently inflated and that the valves are set to green.


Check that the engine is bolted to the transom and the chain is secured through the shackles.


Check that the fuel is oiled and that there is enough for your journey plus a generous reserve.

Boat Pole

Check that this is securely fitted and carries:

  • A radio, either a handheld in a waterproof case or the built in GMDSS radio. Check the battery is charged. Check that the GMDSS radio antenna is securely fitted.
  • Charged up battery for the echo sounder.
  • The GPS (only in the big boat pole) should be in the box alongside the GMDSS radio, connected to the interface cable and have charged batteries.


Each boat should have one big brown tube containing:

  • Full oxygen cylinder with regulator
  • Cylinder key to turn cylinder on
  • Face mask
  • Non-rebreathing mask

And one small brown tube containing a spare full oxygen cyliner.

Tools Dry Bag

This should contain:

  • A black cylinder holding tools, spare kill cord, spare starting cord and a smaller white cylinder containing spare spark plugs and boat valves
  • Spare inflation tube
  • Spare fuel line

One per boat.

Flares Dry Bag

Contains rocket flares, white smoke flares and red handheld flares (one per boat).

First Aid Dry Bag

Contains disinfectant spray, waterproof plasters, waterproof tape, dressings and bandages, space blanket style jacket (in orange vacuum packed wrapper) and a cold pack. What you can do at sea is limited – the shore first aid kit is more comprehensive.


Two oars per boat. These aren’t really any good for propelling the boat (putting people with fins on over the side to tow is much better) but are useful to stop the tubes hitting rocks if you get too close.

Tow Rope

One between two boats. If you ever need to be towed by another boat use our tow rope and pass it to the other boat. If you accept a line from the other boat then you are deemed to be no longer in control of your vessel and the other boat can claim salvage rights. Negotiate what payment will be required for the tow beforehand to avoid being handed a large bill back on land. Don’t worry about this in a real emergency!


  • Flag – one per boat
  • Anchor crate – one per boat
  • Shot crate – one between the two boats
  • Boat pack (contains tables and details of the dive sites) – one per boat
  • Bottles of drinking water for each boat