You can get through at any time, especially if you're using Navionics or similar.......Even high water you can hit stuff!
The tides can be really fast but nothing a reasonably powerful craft can't handle easily.
It's fairly weatherproof too, being set deep down with high ground around.
I have a yachting manual which gives good advice on the route through.
I lived in Menai Bridge for 20+ years and spent a lot of time out on the Straits, generally in 4-8HP SIB's though. You'll be absolutely fine if you stick the middle of the channel generally. Two places to watch out for though are:
1. The sand bar's off Beumaris and Gallows Point - got stuck there when my sister drove into one and broke the pin on our Seagul engine, we then havd to paddle all the way over to Gallows Point (Dickes boat shop at that point) and buy a new one. The conversarion in the boat went:
Dad: Look out for the 1/2 mile long sand bar
Sister: What sand bar
Boat: BANG
Dad: AHHHHH, what have you done....
2. The Swellies at the mid point between the old and new bridge (I'm sure they have official names but that's what the locals always called them).
The Swellies are close to the surface and will cause a lot of damage, the tide runs fast between the bridges so just take care. I'm sure an IMRAY chart will show you where exactly.
I'd personally say it was safer to traverse the area at low(ish) tide as everything you can hit will be exposed and in sight.
Enjoy you're day and safe passage.
Afterthought, further down off Caernarfon there are big sand bars also, you can see them on Google Satellite view.
If you wait long enough you will see other boats go through and you can follow them. If you go through at low tide you will see quite a lot but you need to be aware of platters rock as this might just be below the surface. Otherwise follow the above and you will be fine. It is always good to get someone to show you.
Couple of other things. Watch the 5 knot limit at Port Dinorwic. You may get caught for speeding if you do 20knots! Caernarfon Bar can be as tricky as the swellies. The buoys have just been moved and the new chart is here
The best way of going through the Straits for the first time is with Chris Caton, who has studied the Straits in detail at low and high water. He is your man if you want a guide. He is contactable on here.
The chaps at Seawake Ltd, Dave Manning and Phil Sharkey, Advanced Powerboat Instructors based at Menai Bridge are also highly experienced and are contactable on here.
RIB Saffron
Carpe Diem
