i assume you mean you require assistance on the hairline cracks, many products exist from the major companies to deal with Hairline cracks you will need to look in your area but BASF,Mapie,Bondall and Sika are some in Australia
, be carefull to ask and ensure you receive products that will react in salt water
as many are made for potable water "domestic tank repairs" and wont work
Mostly the products to avoid are the ones that require "free limes"to be present to activate the chemical process if the boat
is older, many of the available free limes will not be sufficent (these mostly need 150mm of solid poured concrete no older than 10-15 years,but not always.)
You can have a sample of your boat tested to ensure complete compatability with all the products you are using by a concrete testing laboratry.
when you have repaired All the damage some of these companies have cement products that can coat the outside of your hull
it is applied as a 3-6mm concrete coating and will waterproof the entire hull , then your antifoul etc can be applied over that (Mapie smart is also flexible, pronto is not).
if you select the correct products and use them as per the details thi will be a fairly simple process but will take time for curing and overcoating
i hope that is of some help