My tips are also under the water. they have internal flaps and I also installed the external ones. Once again IMO your major concern is lake water not cooling water. If your somewhat concious of this you shouldn't have a problem.JMO Now if you have alot of compression with a big ol knarly cam. Thats a diffrent story
Compression is over 11:1 and the cam is a large solid roller. Ill get specs.