I have used these in the past, from Hughes Aircraft Kits (https://hakits.co.uk/?page_id=372), and no complaint's so far.
Universal Model Boat Stand,
Medium for hulls up to about 5″ beam. £8.00
Large for hulls 5 – 9″ beam £10.00
XL for boats over about 9″ beam £11.00
These are available to purchase from there eBay store,