hello im looking for some advice on engine mounting angles im running a 175 hp johnson on a 1975 hydrodyne18 ft problem im having is at full trim up the boat still wants to noise into the water causing low speeds, prop cavatation on turn, and cant see for the water splashing me in the face. can post pictures if u would like to see set up need to get lot more trim out of her for better preformance and noise lift what wedge degree should be in between engine and transom . took some pictures of the boat this one isat full trim up not much for trim angle
It sounds like you have more than a trim issue. Run a string down the keel and see if it is straight. Put a 3 ft straight edge on the bottom at the stern and see if it is straight. I actually have a wedge in my boat for more tuck. The boat runs best at speed with the motor perpindicular to the water. I also have a bow fuel tank. Has your boat had any major repairs? Is the hull solid? jim
Have you verified that the trim stays up under load? I had trim issues at one time and under load the force from the prop would push the engine all the way down to the bottom of the trim range. At the trim angle in your photo, my 18 (200hp Johnson) will skip across the water (relatively speaking - it's a Dyne after all) and be terrible for skiing. Mine also has a bow mounted tank and I have NO problem lifting the bow, even with a full tank, given the angle in your photo. Regards, Scott
Hi, I test drove your boat on the Red River years ago when it was first for sale. Nice Dyne BTW. I wasn't very aggresive with the boat when I test drove it cause the owner was in the boat with me, plus the motor had just been rebuilt and was still being broken in. I remember that the top end was somewhat slow for a 175 but I don't remember what prop was on the motor. I agree with Jim, this must be more than a basic trim issue. There should be more than enough trim angle to keep the nose from digging in. Sometimes when a trim system runs low on pressure or low on trim fluid, bumping the power up in a turn creates just enough force on the system to move the motor back down to the stops. Watch for trim movement next time you put your boat in a tight turn. Prop cavatation is most likely more of a prop issue. I replaced my 3 bladed prop with a 4 bladed one on my Optimax and the cavatating stopped, even in very tight turns. I'll default to other members on this site who know a lot more about rigging motors than I do. I'm glad to see that this boat went to someone who is looking to take care of it. Kevin
All Hydrodyne boats that run into the mid 50's usually require only a little trimming up to obtain this performance. This sounds like bow steer. Hydrodynes bow steer when there is too much bow in the water at speed. Normally when you get into the 30's you can trim the motor up a little and feel the boat level out and steering effort goes down too. Bow steer normally goes away with the trimming of the motor. If you over trim the motor the boat will bounce at higher speeds and cavitate in the turns sometimes. Bow steer can be caused by several things. Excessive weight in the front is one cause. If you have a full gas tank up front that might contribute or cause the problem. The hull could have a "hooK" in the back. This can be checked with a 4' or 6' level or straight edge. Put one end on the bottom at the transom and the long part running lengthwise on the boat against the hull. The edge of the level and boat hull should touch all the way if there is no hook. Check several places from one side to the other. If this all checks out OK the boat hull is likely flexing while under way and the boat hull has a major (expensive) problem I'd guess! Consult an expert in boat hull repairs.
