If you are decided to visit Ko Lanta by sailing boat is the best place to stay down there for the night..You can reach shore by zodiac easygoing. After can visit many nice restaurant s or even visit 7 eleven..
North of Ko Lanta not so good for sailing boat s, because of low electricity lines near Saladan town:) you can risk in low tide:) but now body whant to joke with power which supplying all island:)
The best Kantiang Bay, because of great depth and close lagoon:)
Have fun , dear sailors:)