Hi Philip W
I assume that you plan sailing between the islands and not from continental Europe to the Canaries, as there won't be much time for sailing between the islands in 8 days when starting from Gibraltar or even from further away...
Guess, you already tried the Cruising Wiki
with some valuable info!
Northeast trade winds predominate the Canaries. If they are interrupted by low pressure systems moving southward, bringing gales of up to 35 kn of wind from south through southwest to northwest, you do not want to sail. But then the swell can be a problem in the harbours and marinas (mostly on the south coasts of the islands), where you seek shelter. This can happen during the winter months. Monitoring the weather forecasts is a good idea.
But most times you will encounter these norteasterly trades. Sometimes stronger, sometimes weaker. The speciality about sailing BETWEEN the island are the wind acceleration zones to the southeast and the southwest of all islands, but especially developing close to the higher islands of Gran Canaria and Tenerife: Winds can increase from 5kn in lee of the islands to 25kn (or more) once you reach the acceleration zone. This change can happen within a couple hundred meters – when you can see, where the wind starts funneling, shorten your sails.
Take also in account that there is a southwest setting current of up to 2 kn, between Tenerife and La Gomera up to 4kn under the La Gomera coastline.
That leaves you in the situation to do some beating to windward right where the trades are blowing hardest when you want to sail from one island to another. Generally it is a little easier to sail the islands starting from Lanzarote to Gran Canaria, Tenerife or further on, than to take the opposite route.
In any case you should prepare your boat for heavy weather when intending to sail between islands. And at night the wind is not blowing as hard as during the day: We did our passages between the islands at night.
In general harbours and marinas are on the south side of the islands, except the big harbour of Las Palmas (Gran Canaria) and the two little harbours of La Palma: Santa Cruz on the east coast and Tazacorte on the west side (with a marina built in 2010).
The Canary islands do not have anchorages that are shelteres against all winds. Most anchorages are better used only as day anchorages. But we tried these under stable weather conditions (northeasterly trades) even over night: west of Punta Papagayo (Southcoast of Lanzarote) and south of Isla de Lobos, close to Fuerteventura – but here watch for possible ground swell – then don't pass or even anchor between these islands – then it is also difficult to enter the harbour of Corralejo on the north side of Fuerteventura.
There are some nice anchorages (except in southerly winds) on the southeast coast of Isla Graciosa (north of Lanzarote), but we did not try these.
The south coast of Fuerteventura is fine for day anchorage, maybe over night during stable weather conditions.
As Gran Canaria is almost perfectly round shaped, there are no ancorages that are free of any swell. Small anchorages are mentioned on the south coast close onshore and behind breakwaters. Years ago the very few acceptable achorages on the south coast were taken up by long term live aboards - I'm not sure how this is today.
We did not try Tenerife.
La Gomera only has day anchorages on the south side we tried and liked very much. The harbours of Santiago de Gomera (south) and Valle Gran Rey (west) have bigger breakwaters (or what is left of it) where you can try anchoring. But most times the inner part of the basins are occupied by fishermans moorings and anchoring was not very comfortable because of swell...
We have not yet tried El Hierro.
A book worth for planning in advance and having on board is Atlantic Islands
issude by the Royal Cruising Club Pilotage Foundation (Imray Laurie Norie & Wilson Ltd, UK).
Wishing you 8 days of nice sailing and maybe you have some up to date info as a contribution for the Cruiser wiki!