So after a few frustrating weeks of engine diagnostics, I have finally succeeded in solving the great mystery of the '72 Evinrude 25. During that time, I had installed a set of the Smart Tabs SX, the 9510-30's, the boat in question is a 14' Johnsen skiff, mostly flat bottom, with around a 58" beam at the transom, 62.5 midship. Some tracking strakes on the bottom of the hull, but flat, more or less.
I had an anti-porpoise plate on the lower unit before, and still had a porpoise issue, I could fill a bucket of water and stick it in the bow, but I wanted a more permanent solution. I had also read that on small boat transoms, the plates can cause some serious damage over time. I had read good things about Smart Tabs, so I figured I'd give them a go!
Last evening was the first time I had the boat out since all of the work and the tab install, and unfortunately, things are not performing as I hoped. Now, just a disclaimer, I am not bad mouthing the company, I have sent them an email and hope they can help me out, but I wanted to ask on here to see if I can get some suggestions from you folks too, as maybe I just have something set up incorrectly regarding my prop height.
Basically here is the deal, with the tabs down(I also bought the PR500 brackets, as I regularly fish very skinny water and need to be able to get them level with the hull), I have so much stern lift that when attempting to power up onto plane, the bow of the hull digs, very heavily, into the surface of the water. I trimmed my motor all the way out to try and remedy this, and while I was able to run this way, slowly mind you, as I still couldn't get the hull to plane out, if I were to come off the throttle, the boat dives dangerously hard into the water as the tabs grab and pull the stern up and push the bow down.
I spent the rest of the evening with the tabs in the "up" position, there was no way for me to run with them down.
My thinking is that my prop is not able to get itself any bite, the factory cavitation plate built into the lower unit(right above the water pickup) is level with the bottom of the transom, and I never had an issue with it's location before. But I can audibly hear it ventilating while trying to run with the tabs down. Turning was almost out of the question, as it was FAR worse while attempting to change direction. Do I need to lower my prop? It would seem odd that I would need to do this, as my understanding of trim tabs is that they should channel a large amount of water into the area where my prop is located, thus supplying it with enough water to get a good solid bite, even with where it is located in relation to the hull.
I tried every setting on the tabs, 1-5, which had no effect. The cylinders move freely, and everything is installed according to the directions. They are about, if I remember correctly, 5" from the outside edge of the hull. There is a good bit of room from the edge of the tabs to the prop itself.
I will supply some photos later on regarding install location, and the location of the lower unit in relation to the hull. But any helpful tips you guys can send my way would be great. Thanks in advance.
Steve
I had an anti-porpoise plate on the lower unit before, and still had a porpoise issue, I could fill a bucket of water and stick it in the bow, but I wanted a more permanent solution. I had also read that on small boat transoms, the plates can cause some serious damage over time. I had read good things about Smart Tabs, so I figured I'd give them a go!
Last evening was the first time I had the boat out since all of the work and the tab install, and unfortunately, things are not performing as I hoped. Now, just a disclaimer, I am not bad mouthing the company, I have sent them an email and hope they can help me out, but I wanted to ask on here to see if I can get some suggestions from you folks too, as maybe I just have something set up incorrectly regarding my prop height.
Basically here is the deal, with the tabs down(I also bought the PR500 brackets, as I regularly fish very skinny water and need to be able to get them level with the hull), I have so much stern lift that when attempting to power up onto plane, the bow of the hull digs, very heavily, into the surface of the water. I trimmed my motor all the way out to try and remedy this, and while I was able to run this way, slowly mind you, as I still couldn't get the hull to plane out, if I were to come off the throttle, the boat dives dangerously hard into the water as the tabs grab and pull the stern up and push the bow down.
I spent the rest of the evening with the tabs in the "up" position, there was no way for me to run with them down.
My thinking is that my prop is not able to get itself any bite, the factory cavitation plate built into the lower unit(right above the water pickup) is level with the bottom of the transom, and I never had an issue with it's location before. But I can audibly hear it ventilating while trying to run with the tabs down. Turning was almost out of the question, as it was FAR worse while attempting to change direction. Do I need to lower my prop? It would seem odd that I would need to do this, as my understanding of trim tabs is that they should channel a large amount of water into the area where my prop is located, thus supplying it with enough water to get a good solid bite, even with where it is located in relation to the hull.
I tried every setting on the tabs, 1-5, which had no effect. The cylinders move freely, and everything is installed according to the directions. They are about, if I remember correctly, 5" from the outside edge of the hull. There is a good bit of room from the edge of the tabs to the prop itself.
I will supply some photos later on regarding install location, and the location of the lower unit in relation to the hull. But any helpful tips you guys can send my way would be great. Thanks in advance.
Steve