[tm3]

Paul,
From what I can remember and personal experience your insurance co. is responsible for you & your insured boat. It is their responsibility to make you whole, meaning return the boat to the condition it was in at the time of the loss. If the damage is in excess of the boat value as cited in your policy then they can consider it a total loss and pay you only that amount. They might add extra depending on what was in or on the boat at the tme the loss occurred if you can prove it meaning receipts, etc. and any additional coverage you might have in the policy. ( personal property, etc. )
If you are nt satisfied with the numbers from your ins. co. you also have the option of getting your own estimates and challenge your ins. co. in an "arbitration" request. Meaning a neutral person decides after your ins. co. and your independent adjuster/estimator provide him/her their cases.
Regarding the wording "loss of use" that means paying you for the time that your boat is out of service and I was under the assumption that "loss of use" is related to "business use". Again meaning your boat is used for business purposes. As for "appearence allowance", that I never heard of.
But those terms give me the impression your boat is repairable.
Has the other insurance co. contacted you directly if the loss was the result of their insured?
Normally he other insurance should have contacted you if it was their insured''s fault and surveyed the damage giving you numbers then leaving it up to you as to accepting their offer or going through your ins. co.
There are other issues such as "no fault", policy language, etc. that can come into play. You really need to read your policy many times and make sure you understand the wording and what it means.
Possible a little more info. about how the loss occurred and extent of damage might help as "hamiam" suggested.
Again I cite ugh, "attorney".

tm3