Bayliner 38" Modification

[Redneck2]

I am planning to extend the stern of my 38" bayliner "with tunnel drive" 4'.

Vitals: Year 1983

WaterLineLength 38'2"
Beam 13'5"
Weight 22,000
Power Twin Chrysler/Mitsub in line 6-cylinder diesels,331 cubic inch
Propellers, 19X18 four bladed through 2:1 reduction gears
Shafts & propellers housed in tunnel drive pockets
Hull..modified hard chine goes on plane at approx. 2250 RPM
Performance Data: RPM Knots % of top speed
1000 5.4 30
2000 10.0 55
3000 17.4 95
3200 18.3 100
Equipped with (2) complete sets of trim tabs

General Propeller has suggested reducing pitch by at least 2" & small cup

Query: begin the extension at the top of the drive pockets & slope up at approximately 20 degree angle leaving tabs in existing position or leaving the props in current position, extend pockets consistant with present positioning
and move trim tabs to trailing edge of the planned extension.

My gut feel is to extend the tunnels and relocate the trim tabs. However, I do not know if the vessel will be able to achieve planning speed.

Any information, educated guess etc. would be appreciated.

Sincerely,
H. Meier
hmeier29@earthlink.net