[LIforrelaxin]

Cate,

Despite what many have said here, you will find the the 70 h.p. is plenty of power for the pontoon boat. With the only issue being that you will not be moving at 30 or 40 mph. You should be able to get a nice cruising speed out of it though.

What you may find is that you need to try different props. To find the one that works best.

Now as others have said to avoid issue on rougher days, you will have to work with how to distribute the weight in the boat.

Finally before re powering use the boat with the 70 h.p. on it and decide if it is adequate or not. That way you will know what to look for when you re power. Some thoughts on repowering an older boat... first look at options, if the 70 h.p. is adequate for you needs, Mercury make a big foot option that you can get on I believe a 60 H.P. that will give you more pushing power, as it spins a bigger prop. I had a friend that had a 22 foot pontoon, on Lake Champlain, with a 50 h.p. merc bigfoot, and it was great...