SeaSeal Ltd has been founded by a partnership between the owners of TG Stamping and Machining Ltd (TGS) and established marine experts. TGS has a 70 year history of forging very high quality non-ferrous components for high risk, critical applications in the gas, oil, fire control and marine industries, where component failure is not an option.

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This history and experience has been brought to the design and manufacture of a new seacock of the best quality to protect boats and their crews.

Boats live in a hostile environment and spend much of their life unattended. Anything that goes through the hull presents a leakage risk, which is why any pipe going through the hull below the water line has a seacock so that it can be sealed when not in use.

Failure of a seacock can be a terminal event for a vessel leading to loss of life and property. In our view this is not a component where any compromise over quality can be tolerated. It is amazing that modern boat builders are prepared to fit unsuitable items, more suited to domestic plumbing, with a limited life expectancy in order to save a few pounds in production costs on new vessels. These failings show up when the boat is as little as five years old when these unsuitable components start to fail in operation.

The aftermarket is similarly poorly served with most chandleries stocking inferior products with questionable provenance, made from materials unsuited to the task and often making inaccurate claims as to the materials of which they are made and methods by which they are produced.

Our testing has demonstrated that even trusted established brands are using basic brass of unknown origin rather than marine grade metal.

The general quality of components used for marine plumbing fittings, controlling the opening to sea (seacocks) is surprisingly poor given the catastrophic consequences if the parts fail. After market parts are usually imports with no traceability or provenance and much of the original equipment on pleasure vessels is off the shelf and neither of high quality nor always suitable for the task in hand.

TGS has an established reputation in the manufacture of high quality non ferrous components for marine applications and has now teamed up with a well respected marine surveyor to design and build a top quality range of brass products to address this need.

Forged or Hot stamped manufacture

Our product is forged or hot stamped. Under this process the metal is heated and then stamped with up to 1,000 tons., causing it to ‘flow’ to the desired shape. This process strengthens the metal at the molecular level and produces a consistent, strong component. Most products of this sort are cast. This is a process where metal is melted and then poured into a mould. This produces a weaker product, which can be more porous, brittle and may contain voids, which weaken it further.

Traceable DZR material

Metal fittings coming into contact with seawater are highly susceptible to corrosion and although brass does not rust in the same way as steel it can loose its zinc content and so degrade and become brittle. Our product uses traceable, high grade DZR brass (or dezincification resistant brass) and this reduces the risk of corrosion significantly, especially when it has been forged.

Built in anode

The corrosive effects of sea water are exacerbated by boats themselves in that the electrical systems of the boat may ‘leak’ causing a current through the boat’s metal fittings to earth through the water. This makes the metal fittings act like the reverse of an anode in electro plating and so instead of metal being deposited on the fitting it is dissolved, so the fitting can literally melt away. Fitting sacrificial anodes around the boat near metal fittings is the usual way to guard against this by letting the anode dissolve rather than the fitting itself. It is also common to connect metal parts together (bonding) by wire connection. Our product has its own sacrificial anode screwed to the base of the skin fitting to protect the entire assembly and negate the need for bonding.

One metal design

A further dezincification acceleration risk occurs where a number of different metals are used in a fitting and this is frequently found where, for example, a steel ball is used in a ball valve type brass seacock. Our product is made from DZR throughout and the central core is also a DZR brass cone. Again this reduces the risk of corrosion, whilst adding strength and quality.

Adjustable action

The brass cone, referred to in point 4, is held in place by a disc that screws into the seacock and this allows for adjustment of the action. In order to remove any risk that the screw in disc is loosened too much and that the cone comes out of the seacock, the mechanism is held in place with a yolk that is screwed into the seacock body. The entire assembly can be removed for servicing whilst the boat is ashore and adjusted at sea.


The seacock can also be greased whilst in use to further reduce the risk of sticking and becoming stiff.


The greasing points can also be removed in order to drain the seacock for winterisation purposes.

Unblockable at sea

Where seacocks are infrequently opened and closed and given the hostile environment where they operate there is always a risk of sticking. This is a major disadvantage of the ball valve type assembly, which is now commonly used in seacock applications. The reason for this is twofold. Firstly when a ball valve is operated, anything in the pipe at the time is free to flow around behind the ball, which sits in a void in a pipe between two seals. The handle mechanism is also within this void such that the mechanism is then permanently immersed in a mixture of seawater and corrosive waste (subject to the seacock’s application). When corrosion sets in it is the handle mechanism that then fails.

The second reason for the unsuitability of ball valves is that when the valve sticks the only option for freeing it is by extra pressure on the handle. This inevitably leads to the handle snapping off, especially if has been weakened as above. This leaves an inaccessible mechanism locked in position. If it is open then the system is open to the sea, so negating the very purpose of a seacock. If it fails closed then there is no water supply, which in the case of an engine inlet makes the engine unusable. The SeaSeal product has a mechanism so that it can be freed at sea with no disassembly and no leakage to the bilge.

Installation options and ease

The product has been designed with a number of advantages in installation.

  • The SeaSeal seacock can be installed by one person
  • The seacock can be set up to face in any direction for ease of installation and subsequent use.
  • The handle can be set to operate either to left or right to further aid usage and installation.
  • The top of the seacock has a screw in spigot so that the pipework can either be taken out vertically or, if space is an issue, an elbow can be used instead to take the pipes away to the side.

British made to ISO standards

The seacock is made by us in England from traceable guaranteed material in our ISO accredited factory. See for details of our manufacturing operations.

Range of accessories

We also produce the associated pipework, joints and skin fittings of the same material and quality.

Competitive price

Because the product is manufactured by us we are able to price it competitively with inferior products.

Ball valves

This is the most common variety of seacock. It is essentially a ball sitting in a pipe joint between two seals and is operated by a linkage through the side of the pipe. The joint is tightened so that the two seals are pressed against the ball on either side. When closed it forms a very tight seal and this is its primary advantage. It is widely used in domestic plumbing applications and can withstand high pressures. The valve also has the advantage that the handles are set so that they align with the pipe when open and across it when closed. This gives a clear visual indication of whether the valve is open or closed in normal use.

However it offers three major disadvantages, which are particularly pertinent in a marine application.

The first is that when the valve is operated the contents of the pipe flow around behind the ball. Where the pipe only contains clean water this is not a great problem but in a marine application it means that the mechanism sits in a mixture of seawater and waste which is highly corrosive.

The mechanism cannot be disassembled and so no servicing or unblocking is possible.

The mechanism is the weak point and when the valve seizes up it can only be freed by increasing pressure on that mechanism. The mechanism then fails leaving the valve in whatever position it was in at the time. So it will then be stuck open or closed or partly open. It will also not be clear to the operator what position the valve is in once the handle has deformed and sheared off.

If this occurs at an engine intake and the valve fails closed the engine is inoperative and if it fails open then the system is open to the sea. The only remedy is to lift the boat and replace the valve ashore. To add to this problem the handles and operating assembles are usually made of mild steel, which corrodes in the hostile environment of a bilge.

These features make this kind of valve fundamentally unsuitable for connection to sea toilets, holding tanks and engine inlets.

Gate valves

This is a traditional design for a seacock and operates by sliding a gate across the pipe. These are expensive to make and bulky. They also do not offer a visual indication of whether the valve is open or shut but they are sturdy, reliable and long lasting.

Cone valves

This design has a cone inserted through the centre of the valve body. The cone has a bore through the centre so that when it is turned through 90 degrees the pipe is sealed off.

It has the following advantages:

  • The handle gives a visual indication of whether the valve is open or shut.
  • The handle mechanism is strong so that should the valve become stiff the handle will not break off when pressure is applied to it.
  • The cone can be removed for cleaning.
  • It can be made of one material, so reducing the risk of corrosion from mixed metals.


  • Challenging to produce, requires precision machining and is preferably forged, rather than cast.
  • Holds less pressure though the pipe than a ball valve. For a seacock however the pressure is not that great because even in a large vessel the seacock will only be one meter or so below the water. The pressure that there is however is constant and relentless and a cone can deal with this.

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