Hi Louis
Many options depend upon the type of use for the boat, some of which you will not discover until you've owned it - and as Graham, I, and many others have discovered, the BayRaider's versatility lends itself to continuous evolution, hence Graham's comprehensive list with many good ideas. My advice would be to consider carefully what you intend to use the boat for and postpone options that can easily be retrofitted as you evolve your use of the boat. Otherwise you might end up with a garage full of redundant kit like mine!
There are some items I definitely would specify on a new boat, including some items already listed by Graham. Disregarding budget and in rough priority these are:
1) A well built, easy-to-use trailer.
Bare boat and trailer combined weight is uncomfortably close to the 750Kg max for unbraked trailers (and the max unbraked limit is even less for many quite large cars) so a braked trailer is very desirable.
The boat should be easy to launch and recover WITHOUT ever immersing the wheel hubs in water. Well set-up swinging cradle systems are good.
Large wheels and softer suspension will protect your boat.
LED trailer lights save a lot of unreliable lighting board misery.
There is probably more about trailers on this forum than any other topic - which does not mean BR20s are difficult but a good trailer makes a big difference to your enjoyment of the boat.
2) A reliable, easy to manage and quiet outboard motor (2nd biggest topic?).
For cruising inshore waters an electric outboard might be ideal. Quiet and easy to use. I've not used an electric outboards for inland waters but would have one if I could afford it. Some makes have disappointed (plenty about this on the forum) but modern electric outboard motors range, power and other features are evolving fast and the technology has come of age.
For cruising a heavily laden boat (including water ballast) in open water with strong currents and choppy waves the power and range of petrol engines remains the best option. I'd look for a reliable, quiet and compact type with all controls on the front, including gear lever. Mine is a 10 year old 6HP Tohatsu that in spite of regular servicing fails most of these criteria. Other owners have been very satisfied with modern Yamahas.
3) Large capacity hand pump or electric pump for emptying the water ballast. The cockpit is self draining, if you open the self-bailer in the cockpit sump, so a pump is not necessary for clearing significant water from the cockpit. It is handy though for draining the cockpit sump if the small amount of water there bothers your crew
All the hand pumps I've seen fitted by the yard are too small. Mine is a Whale Titan (big and simple!) that just about fits alongside the outboard (check it will fit with your outboard) I would even consider having two. My pump is set up with a "Y" valve so that I can switch between pumping out the ballast tank and draining the cockpit sump. Some boats are fitted with drain plugs between the water ballast tank and the cockpit sump. In this case, specify big drain plug(s) to the sump- 25mm or more. An electric pump is a handy option and need not be permanently fitted.
The self-bailers are only efficient at speed - when you probably want water ballast anyway. But see below for a useful modification to one of them.
Draining the ballast tank can quick and fun without pumping when recovering the boat onto the trailer. Opening all the ballast tank round hatches, including the two small ones forward ones (to let air in as water exits) and the cover between the cockpit sump and the outboard well. The water whooshes out of the stern as the bow is raised onto the trailer!
4) Maximum diameter ballast tank drain/fill plug that will fit in the drain recess. Small plugs take a long time to fill (and drain) the ballast tank. Alternatively reverse the direction of one of the self-bailers and remove the one-way flap so that it can be used to scoop water into the ballast tank quickly when you need it in a hurry. Remember to close it before grounding the boat, otherwise you may find you have inadvertently acquired a heavy load of sand ballast. Also check it's closed before winching onto the trailer
5) A carbon mast. I have a wooden one that looks nice but carbon is lighter, doesn't warp or crack and require as much varnish. I'd certainly have a carbon mast in future.
6) Spray hood, especially if you do much cruising. The factory fitted spray hoods are excellent - big and simple to use. Its worth wrapping a well tied-tarp over them to protect them from UV and road dirt when trailing or not sailing because taking them off the boat is tedious.
7) Combined chartplotter and sonar scanner.
Not essential but useful and interesting. The sonar is useful to avoid grounding the center board and rudder, even if the chartplotter is not important. The associated batteries and wiring is a faff and fitting transducers tricky, so best to let the yard do this.
I have a 10 year old Garmin 555S which has served well except for unreliable electrical sockets. The charts are now out of date and sonar technology and software has much improved so I might upgrade to:
https://seamarknunn.com/acatalog/Garmin-Echomap-Plus-65cv-excluding-transducer---Preloaded-UK-Chart-SM230_0100189110.html?gclid=EAIaIQobChMI4t2dieqK6QIVybLVCh0cNwz4EAQYAyABEgJL7vD_BwENote this has UK charts, not Denmark.
I've found a sail and mast bag useful. It protects the mast and sails from trailer wind damage and UV light and all the sticks and bits of string can be loosely bound to together and then securely zippered up without a lot of faff. See photo. The wooden crutch is home-made to support a tarp over the whole boat when in storage and not necessary for road-use.
All this is my personal opinion of course and other owners will have many other ideas. Some of us get almost as much fun out of devising gizzmos and "solutions" as we do sailing- myself included.
Matthew
BR20 Gladys