TOPIC: Proper placement of a whaletail on a 61 40HP.

As you can see, I rebuilt the homemade trim tabs the original owner had installed himself on my 1960 Humber Regal and they seem to help planing and handling a bit, but she's fairly flat bottomed so I think it should come up on plane faster than it does and because it's wide and flat it drifts quite a bit while turning (maybe the tabs?) and I can put the gunwales under water with ease at WOT. My Merc buddy Steve gave me these planers(?/wings?what do you call them ?) so I'm going to put them on today and try them tomorrow after some engine work. What is the best position for them ? I haven't a clue. I've seen them back as far as they can go and I've seen them forward. Opinions please. I only want to drill two holes in each side once.

I've never been a fan of those "whale tail" devices, I've seen a lot of damaged gearcases from the forces they create on the cavitation plates where they're usually mounted..

Look into a set of the Nauticus Smart Tabs, I've installed several sets of these on smaller boats over the years and have been very pleased with the improvement in handling and "out of the hole" acceleration.. They're fully automatic and can be fine tuned to the boat they're installed on..

Nauticus Smart Tabs

If you look at the rear of the boat I already have that style made out of marine grade plywood that I copied off the ones built by the original owner. They are fully adjustable the old fashioned way, with a wrench (smiling face, I hate emoji's) but I haven't changed the settings yet to experiment. They are built cheap but do pretty much the same thing I think. Thanks for the tip though. That's the first I've heard of damage but I haven't heard much at all either way yet. I'm tempted to try them for a day, do you think that's a bad idea risk wise ? Thanks for the reply !

P.S. Nice work on that Restorer !

I cannot offer you much advice on the whale tail placement but can offer my experience with turns. The boat I have is flat bottomed with a combination hard/soft chine. The bottom meets the side in a form of S curve where the edge of the bottom has about a 3-4 inch radius which reverses itself to meet the side in a hard edge.

This boat corners very flat and generates enough cornering force that one has to hang on to keep from being tossed from one side to the other. It has no side drift when cornering. It turns so well because the front of the keel is in the water and provides a pivot point for the stern to move around. Trimming the motor out for less wetted bottom would decrease this turning capability but might provide some slight speed increase. I tried trimming out and found that this resulted in porpoising, so normally ran trimmed in.

During the current restoration I found that the bottom structure was not stable. This may have caused difficulty I was having to get on plane and the porpoising underway. Now that I have stabilized the bottom in the restoration, I will be trying different trim angles to see how it affects the ride, handling, and planing.

Well I can speak from personal experience now and they suck ! The boat took twice as long to get on plane and lost about 5 or 6 mph on the top at WOT. I put them on last night, drove to Belwood Lake this morning, launched just after sunrise, and by daybreak I had beached the boat on a really nice little island so I could REMOVE them. This is firsthand and it might be different on someone elses boat but wow what a downgrade they were on my little Humber ! Never again. As for turning with them on it wallowed thru the turns and I could stand it on it's side without really altering course in any measurable way. I'm going to play with the existing trim tabs next weekend and see what happens. Whaletails receive 2 thumbs down from me. Thanks for the reply and have a great day !