Players can only buy the Lady Lumbridge during Dragon Slayer I. If players ask him before embarking on the quest, they cannot board to fix the Lady Lumbridge. He will also tell players that "The ship is not ready yet and Port Sarim's workers are slow so there's no telling how long the ship will take to fix."
The only way of reaching Crandor after the quest is by taking the route under the Karamja Volcano. Klarense may be right in fact, because the Lady Lumbridge is still there. However, Ned is too, but, when going back to Draynor Village, he is there as well.
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After the quest, Klarense gets a new ship (identical to the Lady Lumbridge). When asking about the new ship, the player will say they are able to see where Klarense has painted over Lady Lumbridge and written "Klarense's Cruiser", Klarense promptly responds "Nope, you're mistaken. It's my new boat". As evidenced by the soggy journal, it is discovered that Klarense lied, and it was actually the Lady Lumbridge.