Realistic pericsope and snorkel speeds
 

In earlier threads, there's a consensus that a realistic snorkel speed would be about 7 knots and that you couldn't go flat out with the periscope up either.

What's a realistic max speed for a raised periscope?

The type XXI has a sturdier looking snorkel than the VII and IX. Could it withstand higher speeds?

It's a bummer that we can't put snorkels on the type IIs. It's got the perfect size for sneaking into British ports!

Re: Realistic pericsope and snorkel speeds
 

I recently read that the "Snort" boats (Type VIIC), sailing from Norway (after D-Day) would remain submerged, and raise the Snorkel 4 hours out of every 24, to recharge batteries, air, etc. It would take 2 weeks to travel to their stations in the Channel, a couple of days on station, then 2 weeks return voyage. The max speed for a raised Snorkel was 5 knots.

Lo!
I read, that the Subs; beside the XXI, had to keep an eye on the speed, because it could rip the snorkel off it socket!