My “Cruising Guide to the Netherlands” quotes for this particular area:

This is definitely sailing country. The distances are short and there are many wide lakes, providing you have shallow draught. Yachting facilities are extremely plentiful and this is the place par excellence where a wide variety of traditional Dutch sailing craft can be seen cruising and racing.

I’m very grateful to Anneka Wallace who has put together the following notes:

I couldn’t help doing a little pre-planning also to make sure I hadn’t oversold my cruising ground. The ideal would be to spend some time on the lakes and canals and sample the dutch specialities and if the weather is right, lock out onto the Ijsselmeer and explore some of the old seaports on the Friesian side or cross over to Enkhuizen and/or Medemblik . We used to do this with the barge a lot but I have not been outside with a Mac yet and it would be great to do that in company. We can look at all that later.

Lemmer is just off the A6 dual carriage way from the south and once I look at the available slips will provide driving instructions. The municipal inner marina has parking for trailers/cars etc and a slip but it is quite narrow, although I did consider using it. Read somewhere it was 3m wide. It is build into the quayside on the canal. I’ll go and look and find others in April. Lemmer has a good chandler and many shops and café terrasses to sit and watch the boats go by.
Only drawback is that the prevailing wind is SW and therefore often on the leashore of the Ijsselmeer and it can get rather choppy to get out with a long beat to get to better water. However my thought was to go inland first and go out at Stavoren anyway (for those that wanted open water!!)

Ijsselmeer - although it is not tidal and an inland sea it can turn quite nasty at times. It is very shallow and can quickly produce a peculiar short sharp wave through which our 3m wide but 18m long barge just ploughed on. Many small yachts sail there but I have stood on the dyke and watched them struggle in the short chop – much like Cyan in the picture! Thunder storms are the thing to watch out for in the summer but the weather forecasts are good. VHF, radio, marinas, online.l

Charts
For Ijsselmeer 1810 but I cannot remember how detailed the inland bit is so recommend - The ANWB Friesland B or just the Friesian lakes portion. About 13 Euro and usually available in Lemmer.
No seatoilets allowed in Friesland now. Must have holding tank
Chemical loo points in marinas but I did see a map somewhere with them marked.
Showers/Toilets ashore most marinas have showers and even some villages for those that moor on the town quay.
Passanten - Friesland is well endowed with visitors berths/jetties in marinas. ( no moorings)
Marrekritten – free overnight mooring facilities usually a little outside the villages or in the sticks. Mown banks or jetties with rubbish bins. Marked on chart with red bollard. June should not be too busy yet.
Opening Bridges cost about 2 Euro collected in a clog on a fishing line.
VHF. All channels for weather and bridges listed in Almamak . All inland waterways now have to have ATIS enabled vhf but I don’t know how much they are checking other than a report on a dutch sailing forum.
I have attached the Icom help sheet on ATIS and the RYA link below
http://www.rya.org.uk/infoadvice/boatingabroad/pages/atis.aspx
Fees Lemmer Municipal inner and outer harbour
Visitor berth About €10 per day
Boat and /or trailer parking approx €6.50 per week
Use of Slip approx €4. Pressure Washer €7.50