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You’ll find a drill or a cordless drill in practically every household; anyone who enjoys DIY will probably also have a jigsaw, a sander and an angle grinder in their toolbox. In winter, these tools simply get taken down to the boat. But whilst these tools serve you well in the garage or the cellar, they are sometimes in over their depth when working on a boat. This is because not only do you have to work on much larger surfaces – particularly when sanding – but you’re also dealing with stubborn materials such as GRP or old underwater paint. The futile struggle with small, underpowered tools can be observed in practically every winter storage hall, often coupled with inadequate extraction. Not only is this harmful to health, but the lack of progress is also immensely frustrating.
Which tools are useful and necessary depends on the work to be done and the size of the materials. To fit a few coat hooks below deck or stir up the antifouling in a tin, you don’t really even need a machine. The same applies when applying a sealant to new gelcoat. However, even these jobs are quicker and easier to carry out with a motor.
As our survey (October 2022) of owners of new and second-hand GRP boats and master boatbuilders shows, the equipment deemed necessary varies. There is a general tendency for wooden boats to require more tools than plastic boats
This tool should be available in the home workshop
The cordless screwdriver takes top spot
The ranking of tools, on the other hand, is almost identical. All respondents ranked the cordless drill in first place, followed by a sander or polisher, an industrial vacuum cleaner and saws. Also featuring highly in the rankings were: gloves, lighting, cable reels and accessories such as a folding workbench.
The crux of the matter is that even when it comes to cordless drills, the market is more than a bit confusing. Whether small or large, brushless or with a conventional motor, practically all manufacturers offer models with one or up to four speeds. Added to this are special functions such as hammer drilling or impact driving. The price differences are correspondingly wide. You can expect to spend anywhere from around 30 euros to well over 400 euros.
The situation is similar with sanders, except that here there is also a choice of different types, such as rotary, eccentric, orbital or belt sanders, each of which is available in a range of sizes and power ratings. The top-of-the-range models break the 700-euro mark even without accessories, whilst a basic model costs between 40 and 100 euros, depending on its size.
Anyone who opts for top-of-the-range equipment across the board can be sure that, even when undertaking demanding refit work, they will not reach the limits of their machinery’s capacity. However, they will also need to invest several thousand euros. By selecting equipment tailored to your actual needs, a significantly smaller budget will suffice.
This raises the question of which tools should form part of the basic kit in any toolbox and how to choose the right type, size and performance class. To make the decision easier, we have compiled a list of tried-and-tested selection criteria for the most important types of tools used in winter and on board.
Drilling and screwing on board
The cordless drill is the most commonly used power tool. It also comes in very handy when you’re out and about on board
Whether you’re a professional or amateur boatbuilder, or a DIY enthusiast: if you need to drill a hole in a boat, you’ll reach for an electric drill. At the same time, the tool is subject to relatively little wear and tear during normal winter storage. Unless you’re planning to drill out every single screw on the teak deck in a single day or working with large hole saws, a basic model will suffice. On the other hand, having some power in reserve doesn’t go amiss, and a high-quality cordless screwdriver is a long-term investment. Provided the tool doesn’t fall off the ladder whilst you’re working, the battery life is the weak point.
However, this is certainly a significant factor, at least when it comes to branded tools. Our 18-volt drill/driver from Bosch’s Professional Series shows no discernible drop in performance even after around eight years of mixed use. And, at least for the moment, a suitable replacement battery could be purchased without any difficulty. That may be an argument in favour of a branded tool. However, as battery technology is constantly evolving, this cannot be guaranteed for the future.
Battery quality is crucial
Whether the device actually delivers the promised performance depends on the quality of the battery. The internal resistance is crucial, as it determines the energy storage device’s maximum current output capacity. Unfortunately, this characteristic cannot be determined from the outside or from the manufacturer’s specifications. Particularly with very cheap offers, there is a high risk of buying a pig in a poke, as manufacturers can easily save money by using low-performance cells.
Particularly insidious: the internal resistance of rechargeable batteries increases as the temperature drops and as they age. A machine with a tight power rating may work well when new and in a warm hobby room; in a cold winter storage area, however, it will quickly give out. Charging time can be an indication of cells with low internal resistance: batteries that can be charged in an hour or less are usually fitted with high-performance cells.
Cordless screwdrivers: 10.8 volts, 14.4 volts or 18 volts?
Another factor to consider is the system voltage. This is often used to categorise tools. As a general rule, the higher the voltage, the more power the battery delivers at the same current, and the more power the screwdriver has. Common voltages are 10.8 volts, 14.4 volts and 18 volts, depending on whether three-, four- or five-cell batteries are used.
When it comes to maximum drilling power, an 18-volt model naturally has the edge over a 10.8-volt version; after all, the battery delivers around 60 per cent more power. In practice, however, you don’t need this extra power very often. On the other hand, the 10.8-volt tools are generally much smaller and more manoeuvrable, which is an advantage when working in hard-to-reach places.
Anyone looking for a particularly compact and powerful device cannot ignore what is known as a ‘brushless’ motor. In these motors, the coils are not powered via a mechanical commutator system and carbon brushes, but are controlled electronically. This results in fewer losses, and the motors are smaller and lighter. Furthermore, better magnetic material is often used, which significantly increases efficiency. Brushless technology is no longer reserved solely for top-of-the-range models, but is now also available in 10.8-volt drill drivers. These little tools achieve performance levels that, until recently, were only typical of the 18-volt class.
What to look out for when choosing a cordless screwdriver
- Drill chuck: A clamping range of between 1.5 and 13 millimetres is suitable. The chuck should have a locking mechanism to prevent the tool from coming loose when the direction of rotation changes. Check for concentricity and play
- Torque I: Two figures are usually given. As there is no standardised measurement method, these can only be used as a guide. For on-board use, a ‘soft’ torque of between 15 and 30 newton-metres is suitable
- Torque II: An effective torque limiter protects both screws and tools. In some of the top-of-the-range models, the torque control is electronic and therefore particularly precise
- Voltage: The higher the value, the more power the battery can deliver. Common voltages are 10.8 volts, 14.4 volts and 18 volts. Specifications such as 12 volts or 20 volts are simply rounded-up cell voltages
- Engine speed & gearbox: For the standard drilling diameters on board, ranging from 2 to 12 millimetres in wood, stainless steel and GRP, a speed range of 100 to around 2,000 revolutions is suitable. For screwdriving, the machine should have a slow speed setting
- Engine: Whether to choose a conventional or brushless model is a question of budget and the desired performance. Brushless models are more compact, but more expensive. Check how it starts up – the machine shouldn’t jerk
- Capacity: A large battery makes the tool more cumbersome to handle. For screwdriving and drilling, 2 to 4 ampere-hours are sufficient. If the battery is also to power a grinder or a saw, a higher capacity is preferable
Sanding machines for motor yachts
With a powerful random-orbit sander, you can tackle most projects
The range of sanding work carried out on the boat extends from polishing, through fine intermediate sanding during painting and levelling a teak deck, to really rough work on the underwater hull, when it comes to removing the old anti-fouling coating or smoothing out epoxy filler and fibreglass laminate.
Tool shops stock specialist equipment for each of these tasks; in practice, however, a random-orbit sander is often all that is needed. With sufficient power and the right abrasive, the random-orbit sander is, so to speak, the jack-of-all-trades amongst sanders. With this type of machine, the sanding pad moves in small circles and therefore rotates more slowly, resulting in a very even finish; moreover, the tool is easy to manoeuvre. The path of the small circles is determined by the stroke of the eccentric sander; the shorter the stroke, the finer the sanding finish. For standard boatwork, a stroke of around five millimetres should suffice.
Machines in which the disc is actively rotated by the motor deliver significantly greater removal rate. The best-known example of such a forced-drive system is the ‘Rotex’ from Festool; similar systems are also available as the ‘Turbo’ from Bosch or simply as ‘eccentric/rotary sanders’ from Makita. The switchable rotary action is designed for rough sanding and is extremely effective, though it also makes the machines heavier. Depending on the model, gear-driven eccentric sanders cost around 70 per cent more.
150-series sanding discs – ideal for most jobs
A 150-series model should be chosen for the sanding disc. On deck or on the hull, there are usually larger areas to be worked on, so the large disc ensures faster progress. Furthermore, tradespeople and boat builders work with 150-series machines, which is why the range of professional sanding discs for these tools is the widest. Not only do these have a significantly longer service life than DIY products from the hardware store, but they are also considerably cheaper when bought in packs of 50 or 100.
In terms of weight, the range is from around one kilogram to 2.6 kilograms. This isn’t an issue on horizontal surfaces. On the contrary: the extra weight helps with sanding and dampens vibrations. However, as soon as you have to work on vertical surfaces or overhead – such as on the underwater hull – every gram becomes a hindrance.
Unlike when drilling or sawing, cordless tools are less suitable for use as a main sander. The motor power and the typical continuous use require large – and therefore heavy and expensive – power packs. And, as a rule, the machine is connected to a vacuum cleaner hose anyway.
What you should look out for when choosing a grinder
- Performance: For standard eccentric polishers with a 150 mm plate: at least 350 watts. Machines with a rotation function require twice the power – or more
- Balance: Good weight distribution helps when working horizontally. It isn’t particularly important when working alongside the ship’s side, where low-profile machines have the advantage
- Stroke: For use on boats, a thickness of around 5 millimetres is ideal. With 320-grit paper, you can sand the paintwork finely enough, whilst 80-grit paper provides sufficient abrasion for rough sanding.
- Plate size: Models with 150-millimetre discs are ideal for the surfaces typically found on boats. There is also the widest range of professional-grade abrasives available for these machines
- Extraction: Directly attached collection containers are practical for small, flat surfaces, but can quickly become overwhelmed. On a boat, you should use a suitable industrial vacuum cleaner (see below)
- Convenient cable: Extraction hoses with integrated cable management are available for Festool and Mirka tools. This makes working much more comfortable. The soft outer surface also protects against scratches caused by the hose
- Particularly light: Random-orbit sanders with brushless motors, such as this one from Mirka, weigh half as much as other models – a godsend for overhead work
- Even for heavy-duty use: Machines with a switchable forced rotation feature achieve much greater material removal and are also better suited to polishing
- Universal supplement: Oscillating tools such as the Multimaster from Fein are incredibly versatile. In a test carried out by our sister magazine, YACHT, the accessories for the cheaper models were found to vary enormously in quality. You should therefore ensure compatibility with a brand-name manufacturer
Polishing a motorboat
Without specialised machinery, it is virtually impossible to refurbish older gelcoat. Performance and smooth running are essential
Rotary or eccentric polishers are ideal for polishing. The former work like an angle grinder, but rotate much more slowly. They can remove a great deal of material and are generally used by professionals. There are significant differences in price – but also in smoothness of operation and torque. With rotary polishers, you constantly have to work against the torque of the pad. Poorly regulated motors with fluctuating speeds exacerbate this effect, which takes a lot of effort. Random-orbit polishers work in the same way as the sander of the same name and are easier to manoeuvre. The disc on these polishers has a stroke of up to 21 millimetres, which is significantly more than on an eccentric sander. Consequently, the material removal rate is also higher. Nevertheless, eccentric polishers do not match the polishing performance of a rotary machine. The simpler handling partly compensates for the increased time required for domestic users.
What you should look out for when choosing a grinder
- Speed: The speed range of rotary polishers should be at least 800 to 1,400 revolutions per minute. Around 1,000 watts is the entry-level power rating. Eccentric polishers do not require quite as much power, but rotate at roughly twice the speed. As for weight, the rule is: as light as possible.
Vacuum cleaner for use on boats
A vacuum cleaner with a suitable filter system protects health, keeps the workplace clean and extends the service life of the abrasives
The use of power tools inevitably produces debris. Drilling shavings or sawdust can be cleared away with a dustpan and brush; however, once sanding begins, there is no getting round the need for a dust extraction system. This is because the dust not only clogs the sanding discs, but is also anything but good for your health. The built-in extraction systems found on many machines are suitable only for small, flat surfaces at best. An external extraction system using a vacuum cleaner is far more effective for removing sanding dust. The performance of the filter system is key here. For professional-grade machines, the dust class is specified as L, M or H. This is based on the percentage of dust captured by the filter and the substances it contains. Class L vacuum cleaners must not allow more than 1 per cent to pass through, whilst in Class M, only 0.1 per cent of the dust is permitted to pass through the filter.
These limit values are not binding for private users, but should be observed in the interests of one’s own health. This means that at least a Class L filter system is required. For sanding woods such as beech and oak, or for applying antifouling paint, a Class M system is recommended. However, it is worth checking the technical specifications, as sometimes a machine may not be classified in the higher class even though the filter technology is powerful enough. A filter cleaning function is only useful if you are working without a filter bag.
What to look out for when buying a vacuum cleaner
- Remote control: Metabo’s ‘Cordless Control’ system is compatible with all vacuum cleaners. A vibration sensor on the hose switches the device on and off – ideal for cordless tools
- System vacuum cleaner: When the vacuum cleaner and tools are from the same manufacturer, the connections, suction power and accessories are perfectly matched. These solutions are convenient, but also expensive
- Filters & bags: At least 99 per cent of the dust should be filtered out; this corresponds to Class L. Some vacuum cleaners manage this without a bag. However, bags are useful as they keep the appliance clean and make disposal easier
- Volume: For normal use, models with a tank capacity of between 20 and 26 litres are sufficient. As the filter and dust bag take up space, the actual usable suction capacity is often considerably lower
- Regulation: Limiting the suction power is not strictly necessary, but can be useful if the sander threatens to stick to the surface during fine sanding
- Appliance socket: When working with corded machines, the vacuum cleaner switches on automatically. After switching it off, the vacuum cleaner should continue to run for a few seconds to empty the hose
- Accessories: An extra-long hose makes working with sanders much easier. A round brush is also very handy. Universal adaptors are available for connecting to various electrical appliances
Health and Safety at the Heim Shipyard
Electrics, safety equipment, lighting – useful tips for the weekend workshop
Power tools are useful for making work in winter storage easier. However, in most indoor or outdoor storage facilities, even basic facilities are lacking – such as a workbench with a clamping device, adequate lighting or a power supply. As a rule, you have to work with extension leads. Such exposed wiring is, quite literally, a fire hazard in the event of faults or overloading. Therefore, only use cable reels specified for the total power rating of all connected devices. To prevent heat build-up, the cables must be fully unrolled. Plug connections pose a risk. After a few winter seasons, the connectors can sometimes become corroded. This increases the contact resistance, and the connection can become very hot. In this case, replacements must be obtained immediately.
Health and safety is important when sanding, polishing or painting. This includes not only effective extraction but also personal protective equipment such as painter’s overalls, respiratory protection with dust or gas filters, safety goggles, ear protection and gloves. Whilst solvent resistance is the top priority for painting work, so-called assembly gloves are ideal for many other tasks. They are not waterproof, but they do offer excellent grip and prevent fingers from getting cold.
Hauke Schmidt
Test & Technology editor