First you'll have to check that fishing is allowed, many marinas ban it
Never fished one, so can't comment on how good they are, but on canals where boats are berthed, fish tend to congregate under them so casting close up to the boat is a skill well worth learning.
Quanti Canicula Ille In Fenestra
Species caught in 2017 Common Ash, Hawthorn, Hazel, Scots Pine, White Willow.
Species caught in 2016: Alder, Blackthorn, Common Ash, Crab Apple, Left Earlobe, Pedunculate Oak, Rock Whitebeam, Scots Pine, Smooth-leaved Elm, Swan, Wayfaring tree.
Species caught in 2015: Ash, Bird Cherry, Black-Headed Gull, Common Hazel, Common Whitebeam, Elder, Field Maple, Gorse, Puma, Sessile Oak, White Willow.
Species caught in 2014: Big Angry Man's Ear, Blackthorn, Common Ash, Common Whitebeam, Downy Birch, European Beech, European Holly, Hawthorn, Hazel, Scots Pine, Wych Elm.
Species caught in 2013: Beech, Elder, Hawthorn, Oak, Right Earlobe, Scots Pine.
Species caught in 2012: Ash, Aspen, Beech, Big Nasty Stinging Nettle, Birch, Copper Beech, Grey Willow, Holly, Hazel, Oak, Wasp Nest (that was a really bad day), White Poplar.
Species caught in 2011: Blackthorn, Crab Apple, Elder, Fir, Hawthorn, Horse Chestnut, Oak, Passing Dog, Rowan, Sycamore, Willow.
Species caught in 2010: Ash, Beech, Birch, Elder, Elm, Gorse, Mullberry, Oak, Poplar, Rowan, Sloe, Willow, Yew.