This advice is taken from Sailsetc boat notes and has many valid points for all rc sailing yacht owners.
Care of Moulded Items - excess heat
The items made using pre-preg carbon (Marblehead, Ten Rater and A Class hulls from 2006 onwards) will be resistant to virtually all high temperatures likely to be encountered.
The following applies to all other items:
Epoxy resins offer significant advantages in strength, stiffness and adhesion to fibre reinforcements, over the more commonly used polyester resins. Like most resins they attain 90% of their ultimate strength relatively quickly but curing continues, dependent on temperature, for days, weeks and even months. Distortion is resisted by epoxy mouldings until the temperature exceeds the original curing temperature (normally 20 to 30 degreesC) when further curing takes place leading to minor distortion. Larger distortions will occur if the moulding is loaded when it is heated, for example, if the full weight of the yacht is being taken by the slings of a stand onto the hull rather than onto the keel.
Fins and rudders are particularly susceptible to heat distortion due to the air trapped inside. This expands when heated and will 'blow' the moulding if it is soft. To help prevent this, vent holes are drilled into the cavities at the top of the fin. The fin is particularly likely to become heated to the point of softening because of its colour. This can happen very quickly if the yacht is left on its side in sunny weather, even if the air temperature is not high. The risk is higher in latitudes near the equator and when there is little breeze to cool the surface. If the ballast is poorly supported causing a twisting load on the fin at the same time the fin will twist out of shape. When the boat is launched the new ‘twisted’ shape will be frozen into the fin and performance will suffer.
In our experience a large proportion of heat damage to our mouldings has occurred in the back of cars when, even on overcast days in the summer, sufficiently high temperatures can be reached. A thin white cloth laid over the hull in sunny weather gives good protection. Do not place thick blankets over the yacht.
The thinner and lighter weight mouldings will heat up and distort far quicker than heavier mouldings. Darker colours are affected more as they absorb ultra-violet light better. If the long term appearance of the surface finish is important to you, pay particular attention to keeping the hull cool.
The base of carbon fibre tube rudder stocks is left open so that the stock itself may act as a vent. Do not block these holes.
Take the following precautions:
spray the fin and rudder with grey primer or, even better, white primer
On hot or sunny days
keep out of direct sun whenever possible
avoid placing the hull on hot surfaces
support the fin and ballast evenly when the boat is placed on its side
remove the rig and place boat in a stand between races
slacken rigging loads if there is a long time between races
do not leave the boat in the car without adequate ventilation
care of moulded items - excess moisture
The very fine carbon and glass fibres absorb moisture very quickly if they are not protected by resin. Our hand laminated hulls have a very thin gel coat to keep weight to a minimum and this gives very little protection against moisture absorption. The inside of our mouldings are not given a further coat of resin (as are most mouldings intended for marine use) as this would have a serious detrimental effect on the stiffness/weight ratio. Indeed our reinforcement cloth usually has as much resin removed from it as is possible to lighten the lay up. This tends to create small air voids in the lay up which further increases the likelihood of moisture being trapped in the reinforcement cloth
Cases of osmosis in our mouldings have occurred from time to time when storage conditions have been ideal for this to happen. It is of paramount importance that hulls are not left with water inside after sailing. Hulls should be stored between use in a dry condition and with the servo/winch patches removed to allow ventilation. Moisture will be trapped between the fin box and the fin (and the fin and the ballast) for some considerable time after sailing and will lead to osmosis on the matching surfaces. Where possible you should dismantle fin and ballast after use. Do not trap moist air in the yacht by covering with a cloth between use.
remove the centre deck patches to allow ventilation
avoid laying a hull on warm damp grass
store hull in a dry condition
do not leave damp cloths resting on the hull
dismantle fin from fin box
dismantle ballast from fin if possible