Back in 2005, there was a
good thread on this topic. Skip posted this, which implies that the speed limit is not an issue while taking off or landing. However, part II makes things a bit vague.
Until the first plane is successfully fined for speeding, I wouldn't worry about it. My take (IMNAL) is that they can be restricted from arriving or departing a body of water, but if allowed, they don't have to worry about the speed limit while doing so.
TITLE XXXIX
AERONAUTICS
CHAPTER 422
NEW HAMPSHIRE AERONAUTICS ACT
Prohibitions and Penalties
Section 422:27
422:27 Seaplanes in Operation on Public Waters. –
I. All seaplanes shall be considered boats while in operation on the waters of the state and shall be subject to the marine rules of navigation,
except that they shall be exempt from all laws and rules concerning the operation of boats for the purpose of landing and taking off from such public waters.
II. The operation of seaplanes shall be subject to any restrictions placed upon the use of public waters by rules adopted by the department of safety or the department of environmental services.
Source. 2002, 6:1, eff. July 1, 2002.