Quote:
Originally Posted by seafari25
I think Dave will be modifying his tabs, similar to my Grandfathers so maybe he wont notice any issues.
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Going back a ways here, but I need to give credit where it's due.
In email conversations with strick and Bigfluke over the past two years, it's apparent that the 25 Seafari needs plenty of trim tab authority to function well. For most boats, the closer you can mount the tabs to the chine, the longer your moment arm, and the more effective your tabs will be. But the outer step on the 25 Seafari is only about 9" wide, so if you go as far outboard as possible, only the outer 9" of your trim tabs comes in contact with the water as you start to lower them. As an illustration, here's the port trim tab on my 20sf:
The trim tab isn't much wider than the hull panel, so most of it is in contact with the water as you begin to trim it down. Contrast that with the trim tab on the 25:
On the 25, a significant fraction of the width isn't in contact with the water until you trim it down about 50%. This video is very short, so you may have to play it a couple times, but you can see how the water on the inboard side of the tab is out of the water:
So what is the solution? Well, Brandon's Gramps came up with a good idea. He scabbed a metal plate to his tabs that would follow the step in the VDR hull:
I thought about doing the same thing with some SS sheet metal I had, but I didn't think my material was thick enough. And trying to bend SS sheet to match the hull would have been no fun at all. So I decided to use my recently acquired fiberglass fabrication skills to make some trim tab extensions. I'm happy with the results:
You can see in the picture that I added a SS angle at the outboard edge to catch spray and channel it back along the outer edge of the tab. I'm not sure if it makes the tab extension more effective, but it does stiffen the edge of the fiberglass panel. This video shows the tab extensions at work:
There is a noticeable difference in performance. Trim tab response is much more pronounced. I was playing around with trim on the river last Sunday. With the tab extensions, I got the boat to stay on plane at at 13 mph with less bow rise than I was getting before at 14 mph. It's actually pretty sweet.
More to come... I'm doing the prep and finish work on my swim platform and engine cover. I hope to get those both done in the next week or so. I also need to get my VHF and stereo installed. The VHF for obvious offshore safety reasons, but it's a tradition to listen to classic Buffett when we're trolling for Dolphin, so I've got to get the stereo done in the next couple weeks.
Dave