Does not look like a particulary big job to fix that hole. Make sure you get the boat off the beach or cover it over to keep the sand out, then :

Here are some general instructions for fixing holes and the like (written for fixing H16's and Dart 18 keels to ask questions if you have any):

1, clean out all cracked gelcoat; remove all the fibers that look like they have dirt/grime in them; remove any soggy glass matt (it probably won't really dry properly). Basically remove all the old/damaged areas and make sure you have a clean area to repair. This could mean removing some of the Keel line and having a "Slot" down the middle of the boat. (NOT IN THIS CASE)


2, Make sure everything is clean and dry - VERY VERY important - you can use an Acetone to really clean it and a hair dryer to make sure it is dry


3, If you have an empty slot (if not go to 8) you need to build a backing plate (Thin Balsa can be good for this and then put some string thru it so you can pull it snug to the INSIDE of the hulls by putting your mold thru the slot you have made by cleaning out the old/damaged area and then pulling back snug (this is where the second pair of hands becomes useful !


4, While someone holds the string (and so mold) snug to the inside of the hull, apply glass mat and gellcoat to the hole/slot you have made; Ideally you want to get at least one layer of mat on the inside of the hull - Tip:
Stick the Matt (and gelcoat) to the balsa/cardboard; then put the sting thru and then put this inside the hull and pull it back so the matt sticks to the hull inside. Now while "String pulling mate" holds the string you need to gaffa tape the sides of the hull into the right position so that then the matt sticks it will hold the hull in the correct shape. - This for fixing Keel line cracks on boats like Hobie 16's and Dart's

Basically here you are getting something into the holl and behind the hole so that you can build up layers against it.


5 Let this cure; you now should have a trench that you can fill up and return the hull to the right shape


6, At this point depending on the size of the void left :

7 Big void - long or wide; I would fill this with gelcoat mixed with chopped strand mat (very hard when it goes off) or use gel mixed with Micro ballons (less strong) and then move onto


8. 8 small - Just use filler

9 Top tip 2; when you are getting close to the correct level/shape of the hull; use "grease proof" cooking paper as a outside skin as this will allow you to get a good finish before you need to start standing

10 once you have filled the hole(s) up you need to sand back to the right level; use 400;600 and 1000 wet and dry and then polish if required


So you will need

Acetone (check which one) - some melt gelcoat
Gelcoat of the appropriate colour
Glass mat (depending on the scale of the repair)
Mixing pots for gelcoat - paper are best; just throw away after Mixing sticks - I use wooden sticks you get for coffee at Starbucks and the like - might need a spatula for gelcoat when mixed with chopped strand glass.