O-Jolle material fundamentals by Stefan de Vries
The O-jolle exists since the middle 1930´s and has seen a lot of development.
Starting from massive wood planked boats with unmovable rigs to partial or full plywood/ polyester hulls and decks with full controllable rigs over time.
The fundamental class rules are quite strict and the design heavy, conservative and durable, so as long as a hull has evolved over time she might still be as fast as the newest hulls. There are more than a few 40+ year old hulls that still win major races.
The basic ingredients for a fast hull will always be,
- Allround hull shape
- As light as possible conform class rules
- A logic weight distribution throughout the boat with not too much weight in the ends.
And last but not least make sure all controls are working and fitted in the right place as this boat loves to be tuned continuously.
Again; like any ‘engine’ that is used in competition, keeping a boat fast means spending time regularly on maintenance and updates. The reason older boats tend to fall out is usually more lack of maintenance and updates then out of date design, especially wooden boats do not really get softer as long as the construction is intact.
In history there have been trends with hulls being more flat or round and also for example narrow or wider bows. They all have their advantages and disadvantages but most important is knowing what kind of hull it is you are sailing in and making sure to learn how to use it.
Generally a rounder shaped hull will have a slight edge upwind but will suffer on the reaching and running courses, where the flatter/wider hull will be faster on the reaching courses but will struggle a bit upwind.
The hull shapes with less volume in the bow might be faster in flat water but struggle in the waves and the fuller bow boats opposite. In addition a narrow bow boat will be more sensitive to where the helmsman is positioned and will roll more in the downwinds.
The good thing is in dinghy sailing usually the best sailor wins and there is no substitute for that.
So it is all about learning your boat and how to use it. If you like to go the easier way then buy a more recent hull and if you are not shy of investing time and energy in optimizing your boat then an older hull can also perform satisfactory for a significant smaller budget.
The modern aluminium mast has totally outdated its wooden predecessor, so in general unless you want to go for the classic look do not waste too much energy on a wooden mast.
The function of a mast is to power up/depower the rig in changing conditions so the aim is to find a mast which allows you (with your abilities and weight) to control your boat without throwing away too many hp’s.
Tuning the mast partly comes from playing with side and forestaytension and partly from adjusting the mast itself. This underlines again the necessity to have a proper tuningsystem on your stays!
The most logic mast of choice for long in recent history and still very present today is the Needlespar mast. The Needlespar is constructed from a round tube with a tapered top and a sailtrack attached to it.
Needlespars differ quite a lot in stiffness so if you are either very heavy or very light, make sure you find a mast that matches your weight. Additionally for lighter sailors make sure that the mast has a ‘one piece’ topsection (the tapered part)
Unfortunately the Needlespar mast went out of production in the early 2000’s to be followed up by the Superspar M6 and the AG plus mast. Both shapes are very similar and consist of a dropshape tube with integrated masttrack.
These mastsections are slightly stiffer than the Needlespars, especially in the topsection over the stays-attachmentpoint.
Recently the Emmeti and Spartech ‘Starboat’ mast have been used by heavier sailors.
The Emmeti section is stiffer then all other brands but comes with a nice, relatively soft top part.
Still this mast requires either over average weight and/or over-average technical skills.
To influence a masts performance, it can be reinforced/stiffened by adding extra tubes inside or softened by sanding the tube or softening the sailtrack.
This is quite common practice so do not worry if your mast already has alterations.
There are quite a few sailmakers to choose from, but if set up correctly the differences in flyingshape are small
Important to know is whether your sail has slightly more or less round in the front. This will decide the amount of pre bend that needs to be set in the mast. Lighter or heavier sailors can also play around slightly with this prebend to make the sail easier or more powerful which makes the sail itself less critical then a sail made for an unstayed mast like Finn or OK-dinghy.
Also it is good to know the overall depth of the sail to decide whether a sail will perform better for a lighter or heavier skipper.
Condition specific sails do exists, but most sailmakers have one allround model that covers the whole range of conditions.