Picked up a set of these cheapo 2 way bike intercoms to try out on the boat , do a search for " bike intercom " on www.ebay.co.uk and you should be able to get them for under £20 squid.
Have to say they worked brilliantly , enables easy talking / hearing without the ussual shouting underway
Clips nicely onto lifejacket / baseball hat etc
Well worth a try for the money & the kids think they are great novelty
