Many years ago I wrote an article on this subject in a series called ‘Technical Topics’. It was not as well written as it could be, so this is a second attempt based on a complete review and incorporating facts neatly brought out by Dave Jennings in his excellent article in Bulletin 166. Unfortunately the cheapest and easiest dinghies to obtain second-hand were and still are, although to a lesser extent, the old one-design racing dinghies; many of them euphemistically labelled general-purpose. Accordingly many people, notably single-handed sailors, often end up with a craft which is intended for a crew of two and/or a boat requiring physical strength and fitness that they don’t possess. A high proportion of the technical queries I receive from members have to do with modifying these craft to make them less tiring. However it is not only these craft that can benefit from modification, if easier handling is required.

There is one obvious solution, reduce the sail area, and this is easily arranged by installing an efficient reefing system, although the long mast with its extra top hamper is always there. Not many people are prepared to go the whole way; cutting off a couple of feet and having the sail recut. This is easy enough to do with a wooden mast where the replacement of the sheave is a simple matter; not nearly as simple with a tapered metal one. My belief is that tinkering with a design in this way is not the ideal solution. The craft was designed as a whole concept. The main reason for the ‘tippiness’ of these boats is their light weight as will be explained.

It is an inescapable fact that, except when the wind is coming from dead aft, the wind pressure that drives a sailing vessel through the water is also trying to capsize it. In diagrams 1 & 2 you will see that when a vessel starts to heel the centre of buoyancy moves outwards away from the centreline of the boat. The weight of the craft however still acts through the centre of gravity which remains somewhere near the centreline. A lever is thus formed whenever a boat heels, between the downward thrust of its weight and the upward thrust of the buoyancy. Left to itself the craft returns to the upright, which is just as well if we are sleeping on board! In craft such as dinghies, the crew can act as moveable ballast by sitting on or near the weather gunwale, which obviously strengthens the righting lever. However when the craft reaches a certain angle of heel and particularly when the water starts to flood in, the main buoyancy is supplied by the sealed compartments or buoyancy bags. The centre of gravity of the craft moves further outwards closer to the centre of buoyancy or beyond. In this attitude the crew’s weight no longer helps the righting lever or even reverses it, and the boat then capsizes onto its side. It usually remains in that position because of the resistance of the sails on the surface of the water or because of residual buoyancy in the mast. However inversion of the hull generally results eventually; due to the wind action on the hull forcing the end of the mast under the surface, or due to the relative vertical forces of weight and buoyancy (diagram 3). Leeward movement down wind and wave action complete the operation. If the emergency buoyancy is carried high up near the gunwale (diagram 4), as in many pure bred racing dinghies and the Roamer, then the lever between the dinghies and the Roamer, then the lever between the weight of the boat and the buoyancy could be still trying to bring the craft upright. A compensating advantage when the hull is laid over so far, is that the wind pressure on the sails is either much reduced or vanishes altogether. If only high buoyancy is carried however, the water level in the swamped upright dinghy may be above the top of the centreboard case making baling out difficult.

It will be seen that if a force is seeking to heel the boat, whether it be the wind acting on the sails, or the crew sitting on the lee gunwale, it has to lift a proportion of the weight of the hull if it is to succeed. Likewise any force that seeks to lever the boat upright has also to lift a proportion of the weight. All other things being equal, then the heavier the boat the more resistant to capsize it is. Likewise it is more resistant to recovery. Most of us are happy to accept this as the truth. However our choice between light and heavy boats depends on so many personal experiences and prejudices not to mention availability and cost, that it has produced — and, I am sure, will continue to produce — heated arguments in the pages of the Bulletin. Probably the real reason for the anger is the natural loyalty so many sailors give to their boats; misplaced or not!

Extra weight has another advantage however: it adds to the boat’s inertia, therefore wind gusts take a little longer to take effect and the handling of the craft becomes more forgiving. There again, heavy boats are more trouble to handle on shore. Light boats however, may be able to plane, are quick on the helm — perhaps a doubtful advantage for cruising — and are easier to launch and recover. What would be nice would be to combine the advantages of both types. If we could lower the centre of gravity, the point at which the craft begins to lose its stability would be delayed. We can do this by adding ballast low down. Changing the position of the buoyancy is much harder to achieve in modern general purpose dinghies where the best place for the buoyancy is taken up by seating space.

It has been said that if you add ballast then extra buoyancy will be required. A moment’s thought will demonstrate that while this certainly may well be true, it will not be necessary in the majority of dinghies. The addition of say 100lbs is only the weight of an extra 7 stone crew member. Most two person dinghies are expected to be able to carry two strapping men of 14 to 16 stone. A quick calculation will show that there will probably be enough buoyancy already installed to support a reasonable amount of extra weight. We are not seeking to make our dinghy self-righting. This would only be possible in a special design such as the Roamer. We are merely seeking to delay the dreaded capsize and make the recovery easier for a singlehander if the worst should happen. It is worth mentioning that the recommended weight of ballast for a 12 foot dinghy in the late nineteenth century, according to Dixon Kemp, was 3 cwt (336 lbs).

Position — for obvious reasons ballast must be permanently placed as close to midships as possible, although working craft of yesteryear sometimes had moveable ballast. It must be placed as low as possible; even a few inches of height can render the ballast useless at high angles of heel. High ballast can add to the heeling effect. For an extreme example of this think of a weight at the top of the mast! The ballast should also be placed as near the longitudinal centre of buoyancy as possible thus keeping the ends of the boat light and able to lift to head seas and following seas. Light ends will mean a dryer safer boat and also one which is faster.

From the above one can hopefully deduce that the ideal place for ballast is on the bottom of the centreboard, if one has one. John Perry put it there when designing his own cruising dinghy, and Eric Coleman did the same with the Rebell design. Nevertheless this would be a difficult modification unless the hull was designed with this in mind. Alternatively one can have the whole centreboard of heavy material, commonly galvanized sheet steel. I must admit to disliking the metal centreboard option for various reasons, and in the retracted position its weight is not at the optimum position for affecting the centre of gravity of the dinghy itself. Nevertheless the steel centreboard conversion on the Wanderer has proved very successful. However ballast usually ends up by being ‘secured’ close to the sides of the centreboard case and close to the bottom skin or planking of the boat. I accentuate the word ‘secured’ as heavy weights free to move would be an obvious hazard to any craft. If the point of maximum beam is aft of centre of the hull, then the ballast may well be placed further back. In my Finn slabs of lead fit neatly under the screwed down floorboards aft of the centreboard case, taking up none of the useable space in the dinghy whatsoever.

At this point I should digress about the flip side of metal centreboards. If replacing a wooden centreboard with a steel one one should ensure that the pivot pin area is strong enough, actually I fancy that the most strain comes from resisting leeway, but the extra weight still has to be supported. It also has to have a tackle or small winch to haul it up. Invariably the plate will be thinner than the board although there is no point in a thin plate as, apart from the danger of its bending, it would not have much weight. In order to prevent the plate from banging from side to side — we used to call it ‘bonking’ — one can fill the space with sheets of Formica. This can be attached to the inside of the case (difficult), in the form of large washers around the pivot (may not be large enough to give a reasonable bearing service), or glued to the sides of the plate where it is inside the case. I found this latter solution to work when I bought a dinghy with the plate too thin for the case, but epoxy glue does not work, at least for me, and a contact adhesive such as Thixofix or Evostick is better. I regret however that it may not be that lasting as I found a bit of delamination after a couple of years. If deciding on a steel plate I would recommend the pivot bush promoted by Eric Coleman — see diagram above.

One can ascertain whether extra buoyancy may have to be provided by swamping the dinghy and having an extra person of the weight of the proposed ballast stand in it. Bear in mind that the open part of the top of the centreboard case should remain above water if you want to be able to bale out the boat. Otherwise check that you can seal it off effectively by stuffing in rags etc. as many boats do not meet this criterion, even without the extra weigh of ballast. On the other hand a frightened crewman with a bucket can make up for quite a bit of seepage!

Ballast material — this can of course be almost anything but usually the choice comes down to water, sand, gravel or lead. To my mind the best is lead as it is the heaviest for the volume of space it takes up and can therefore be kept low in the boat; it is however, undoubtedly the most expensive. Water sound attractive as in theory it does not detract from the buoyancy of the hull: it does take up a lot of space nevertheless and stands too high in the boat. Two five gallon containers (100lbs) are an awful obstruction in a sailing dinghy — and who wants 10 gallons of water with them unless they are thinking of having a bath. Any water ballast which is under the surface in a swamped dinghy will have no ballast effect at all and yet this is a time when the ballast could be most helpful. As dinghies can vary in their response to ballast it makes sense to have a trial with bags of sand or gravel first, before planning any more expensive and time consuming alterations. Be aware, however, that ballast appears to have little effect until one reaches a high angle of heel. Reinforcement of the bottom of the hull may be necessary if you use the concentrated weight of lead, less certainly if you use flat bags of gravel or sand. These latter are less easy to ‘secure’ but are less likely to shift at normal sailing angles. You can of course ‘lose’ them, with less effect on the purse. When using lead one should always try to ensure that one edge of your ‘pig’ lodges on the hog (inner keel) in a timber boat. This is the part of the boat best able to carry the weight. If the other side bears on a stringer or frame member or rib you are lucky, but much more likely you will have to glue, fasten or glass in a part rib or stringer to spread the load across the bottom planking or skin. Securing lead can usually be accomplished with a little ingenuity. Lengths of stainless steel shroud plate are useful as they can be easily bent to shape in a vice.

How much ballast? — theoretically the more the merrier, but bearing in mind that the boat should still float, the following is a rough guide based on overall length: one thing is certain is that much less than the minimum shown would have little effect.

12’ 70 to 140lbs 14’ 80 to 160lbs 16’ 100 to 220lbs

Trailing — if you are not sure of the strength of the hull where the ballast is stowed it is better to make some or all of the ballast removable. There is a great deal of difference in the ability of the hull to resist this type of stress when not supported by the water. For the record I have used lead ballast in four different dinghies, and have trailed them all with their ballast in situ as I begrudge any time spent preparing to launch or packing up afterward. So far no trouble has occurred.

Making pigs of ballast the traditional way is to cast them in moulds from molten metal. If you consider heating a quantity of lead a hazardous occupation, then you can build them cold from roofing lead which comes in rolls of various thicknesses and widths. Cut as many leaves of the required size as necessary to get the required depth, clamp them together and drill them, slowly and using lubricant, for the holes for the bolts which will hold it all together. Use 6mm stainless bolts, nuts and penny washers. Then lugging them in and out the boat, you can call them Peter’s pigs, or something like that! If you make them to be easily removable, keep them small, 28 lbs is big enough. Sources for lead include plumber’s yards and foundries — see Yellow Pages. Sash weights of cast iron are sometimes available cheap and this material is slow to rust.

Data

Weight of cubic foot in pounds:

Alcohol 50 Brick 120 Lead 710 Hard coal 47 Iron 450 Softwood 25+ Water 63 Hardwood 40+ Concrete 140+

1 gallon of water weighs about 10 lbs = 0.16 cubic feet.

A slab of lead 10” x 10” x 1.5” thick weighs about 62 lbs; one 10” x 8” x 1” weighs 33 lbs.