help diagnosing cause of problem

[MTboatguy]

If anything, it needs to be at least even with the hull line, myself if I had built it would have had it go up a small amount, but with it being lower than the hull, it is creating drag and is not allow the boat to plane correctly, the higher the bow gets the more it digs in., at least that is what I think based on your pictures.

 

[tonchido]

thanks,i was asuming same thing,bracket is done here in croatia,where brackets are few,so you all think thats root of problem,should i also lower a engine one inch

 

[MTboatguy]

To be honest with you, I don't really see how you are going to get the correct water flow off the transom with the way they built that extension, for some reason, it would seem that only extending the center where the engine mounts, you are creating two reverse flow situations on the sides that is going to create drag. Almost like an eddy in a stream? I hope that is clear what I am trying to say.

 

[tonchido]

spraying of sea around engine is settled by building two platforms for swimming on each side of the bracket,but what is more important is to get rid of spray coming from bow and creating wet ride,this is the real problem

 

[NYBo]

With a better flow from the revised transom, the bow should come up much better. Kinda of like immovable trim tabs.

 

[tonchido]

i forgot the name but until i saw shape of bracket,i was thinking of building on side of boat those spray stoppers,so the sea is not climbing up the bow but guided back toward the sea,wich would be more complicated job,rebuilding transom will be easier task

this boat is just to example what i mean by stoppers of splash

 

[H20Rat]

It doesn't hook down, that is an illusion from the paint angle. (which DOES hook down at the end...) Look at the side profile, it is completely flat on the bottom.

 

[bassman284]

​bracket looks wierd?

What looks weird to me is how that center part of the hull that extends back about a foot and a half from the stern and angles down. That looks like the problem to me and I really have no solution other than take a sawzall and mow it off.

Looking at the second video my thought was that the motor was way too low and now I think I see why. That whole configuration at the back of the hull is putting the motor too low but I can see how if you try to trim up the prop would ventilate. Again, without a lot of surgery, I don't quite know how to make it work. That picture makes it look like you in effect have a big hook.

 

[tonchido]

so i plan on cutting that part,is there any suggestion on what to make sure,i hope its all made of fiberglass

 

[bobdec]

Basically that bracket is acting like a trim tab holding the bow down. It's OK if the bracket adds extra flotation to compensate for the engine position change at static or displacement running. But when on plane you want to make sure it gets out of the water and does not alter the hull design. In your case it looks like it holds the stern up and pushes the bow down, and fights your range of trim adjustment (prop out of water trying to drop the stern, raise bow). The rule of thumb for a bracket is 12 degree rise off of the hull bottom. Using the hull as a level reference (not transom) the rear of the bracket should rise an minimum of 12 degrees up. If your bracket is 16 inches long then the rear should be 16 X (tangent of 12*) or 16 X (0.21255) = 3.40 inches higher than the hull at the transom. You could go more to be safe, but the more you cut off the less flotation you have and that will effect your static flotation. Then you have to consider the effects of hanging the engine 16 inches further back and how that rearward thrust effects the stock hull design and prop height. When the hull is at a normal running angle the flow of water 16 inches behind the transom is usually higher than the stream of water with a transom mounter engine. Again a rule of thumb to raise the engine 1 inch for each 10 inches of setback from a transom mount. You will have to experiment with this.. A lot of brackets are built specifically for the boat hull design. And it's best to copy other similar designs for your boat. Since yours is unique any modifications will be experimental, with better of hopefully not worse results.

 

[tonchido]

thanks,very informative post,i called my fiberglass guy today and he is coming during next week,and i did double check today it is definitely bent downward

 

[tonchido]

today i did hear from previous owner and he told me he used a lot of quartz sand in a bow,to make boat bow heavy,when i asked why he couldnt tell,so i was driving 4 extra persons in bow without even knowing,factory told me they didnt made bracket but the owner told me the saame,boat is just 4 years old and nobody remembers,why would someone put so much sand in bow

 

[smokeonthewater]

Trying to bandaid a poor running hull

 

[MTboatguy]

Trying to bandaid a poor running hull

I agree, something was not right and somebody tried to fix it with a bandaid.

 

[tonchido]

at least was not done in factory,it would be easier if i took it out while still in sea and tried without,but still i feel bracket should be corrected,and sand thrown out

 

[Jeep Man]

With that drop at the stern, is it not going lift the stern and drop the bow when you increase throttle? Fail to see why the bow would need extra weight. In the end, I don't think you will achieve proper plane without modifying the lower part of the extension.

 

[tonchido]

do you think it would be enough to just straighten the bracket with hull,or i need to cut it and lift 2 or 3 inches

 

[smokeonthewater]

Cut enough off he bottom so that it is well clear of the water when on plane.... As described above.

 

[bobdec]

As mentioned previously water rises after it passes the transom, you need enough height at the rear of bracket to clear the water. Min 12 degree angle up, the higher up, the safer you are it will clear water. This is all hit and miss without any real engineering design being done just rule of thumb and hoping it will work.. Looked at some earlier post, loading sand in bow by previous owner would amplify the problem.. Have you had a chance to remove it and see what results are ?

 

[tonchido]

no cose boat is out and costs a lot just to try that,i mean i have to pay a crane,and than again to bring it back ill do the bracket and than hit the sea,hoping for the best,so i dont need to cut bracket where it starts but just make sure it has a 12 degree lift angle,i dont want to weaken construction