Engine mounting height and rear buoyancy

[fishingtoon]

Hello Everyone,
New here! First i'd like to thank everyone that has posted here on this forum. I have learned a lot from you all.

Recently bought my first pontoon.

My pontoon is a 21ft 1996 Northwoods with a 40hp evinrude

Saturday when I had it out for the 3rd time I noticed the rear was sitting very low. To the point water was going over the back of the toons while sitting and moving. When WOT I have a fountain of water shooting straight up left and right of the transom.

There was not much weight in the boat at all. 2 adults 3 very small children (under 4yrs).

On the rear:
40hp evinrude
6 gallon fuel tank full.
1 battery

I also noticed a lot of drag at to mid and at WOT.

Once I got home I really took a hard look at the back of the boat. First, I made sure there was no water in the toons. Took the plugs out along with the air pressure and lifted the front of the trailer all the way up. Notta.

Second, I raised the motor up to the max position. This reduced the drag a lot, But water still like a fountain in the back.

My questions are by the looks of the pictures is my motor still too low? Before it was down all the way now I moved it all the way up, but can't go up anymore with drilling new holes and will need to in order to make the cav plate level with the bottom of the transom.

Second, How can I go about adding more buoyancy to the rear of the boat? I noticed my transom is wide open at the bottom allowing it to fill up with water. Should I close this off? Add a bilge in there? Thoughts, opinions?


Thanks

[Grumman]

so just while sitting, the back of the toons are all the way underwater? is everyone sitting in the back of the boat? That doesn't seem possible unless you have extra weight somewhere. I have never seen that happen on my 24' with 8ppl in the boat and a 50hp motor. maybe you need to redistribute some weight.

[fishingtoon]

Hello Grumman, No. They are not completely underwater. I'd say 3 maybe 4 inches above water with just me on there.

[gowen]

Hello fishingtoon - I have the same problem with my 94 Sylvan, the stern is sitting low in the water, but in my case it is because I replaced the 50 HP 2-stroke with a new Suzuki 50 HP 4-stroke. I had the motor mount beefed up to handle the extra weight of the motor, however I would like to have more buoyancy at the stern. I'm searching for a 19" diameter center pontoon to provide the extra buoyancy. May have to have one built locally. The main pontoons are 22 ft, I would like a center pontoon at least 15 ft long, or maybe a 22 ft unit depending on the cost difference. My boat stays at our lake and is only stored for the winters on the trailer. If I were traveling with my boat on the trailer I would be adding additional support for this new pontoon.