Dockman

Ok I got my stuffing tube down where I want it to be for now. However I did crack the epoxy around the tube. Not sure if that will really hurt anything? I sit it in the water and no leaking. My stuffing tube is right at (9.03 mm) up from sponsons (see picture). I also have my strut at a negative angle for now the (5.47 mm) reading is taken at the very back of the transom bracket down to the strut and the (5.30 mm) reading was taken at the from the transom bracket down to the front of the strut. What do you think about the crack?

Dockman

I think I'll grinder same of the epoxy out and redo it after I figure out where I want it at. I think this is pretty close but may need to drop another 3 or 4 mm.

PEERPSI

Your tilt angle with those dimensions is about 6.5 degrees. What I've been running is about 1 degree. To accomplish that you would need to be about .02-.03 from one end of the strut to the other. Tough to do measuring it that way. Also it does not take into consideration the angle of the transom in regards to the bottom of the hull. What I do is use a protractor sitting on the same flat surface as the hull bottom.

I don't think the cracking in the gelcoat is much to be concerned about, mine was the same until I had the hull repaired. Didn't leak either.

With a 72 MM prop that looks like about 61.6875 % of the radius in the water, near the max. About 6mm spacing between the ferrule and hull bottom would be the max you'd want to go in the water. At this point what I did was 2mm moves up and down to see where I got the best speed.

Looking forward to hearing your results. Mom had a meeting tonight so Dad had the kids. Hopefully I can get in the water tomorrow to see how the rudder changes affect things.

Dockman

Well I' am just going to watch the attitude of the boat this weekend. I have a barrowed motor that is not much (not even a Zenoah) until I get my new RCMK next week. I ran it last night with close to this same setup the boat looked the best that it has. Boat would jump right up on the water and on the pipe.

PEERPSI

I just took another look at your setup and realized there must be something really wrong. Is that the original strut? If so with my 70 mm prop my strut is above the brackets not below. I just measured it and the best spot is 3 mm of strut above the brackets.

Try sitting the hull on a flat surface and then doing the measurement to see if the result is the same.

Dockman

I have a straight edge running across the bottom of the sponson. How much flatter can I get? The picture measuring the stuff tube the boat is setting on a table hanging off 4 or 5 inches.

Dockman

I measured the 3 blade prop at 60 mm.

Dockman

Yes the strut and brackets are stock.

Dockman

Show me a picture of how you measure yours. I think my pictures are pretty clear as to where my setup is?

PEERPSI

Here's a picture of my setup and how I sit it on the table. This ensures the angle of the transom does not come into play. What I actually do is situate it on the corner of the table at an angle in order to get the most surface to work with. I move the boat in until the rudders are touching the table edge. Then I use a metric allen key to space the ferrule up.

PEERPSI

What's your distance from the bottom of the strut bracket to the bottom of the hull? Mines about 5/8" or 15 mm. My prop diameter measures around 60-62 mms but the correct way is to measure the radius, when I do that I get exactly 35 which when doubled gives you the 70 mm in my 7015/3.

Dockman

Looking at the pictures it appears that your transom bracket is mounted lower them mine. Really that is all piontless only the bottom of the boat matters. I'am going out to measure how far up from the tunnel my bracket is at the bottom of bracket.

PEERPSI

There is definitely something different going on there. Look at the spacing between your servo rod transom boots and the rudder brackets. Then look at mine. Looks to me like your rigging is sitting up higher.

Dockman

Ok from my tunnel to the bottom of my transom bracket it is 20 mm and my overall length of the strut is 84.75 mm.

PEERPSI

You're absolutely right, what matters is the amount of prop in the water. This does explaing why some people report that their boat runs best with the strut all the way down while others feel it needs to be almost all the way up. Quite likely a sampling of BJ55's would turn up some serious inconsistences.

One of the ones I found early on was the length of the stand offs for the clutch bell fixture. One of the four on mine was about 1.5 to 2 mm shorter then the other 3. That meant when tightened down the clutch bell would have been sitting at an angle. That lead to the infamous clutch failure in my case.

Dockman

Yes I agree. I guess that is why we always need to measure from the bottom. I had to cut the slot on my strut all the away out at the top.

Dockman

I love the internet.

PEERPSI

Okay strut brackets 12.5 and rudder brackets 25 mm from the hull bottom. 85 mm on the strut length.

PEERPSI

So I'm 3 up and you're 5 down that's 8. Your bracket is 8 higher then mine. In short we seem to find the same place works best.

Now we just need to agree on tilt!

Yep, internet is the best way for like minded individuals to get together.

Dockman

So the only difference is 5 mm on the mounting of the strut brackets.

PEERPSI

What's the total length of your Aeromarine rudders? Mine are 175mm. I'm thinking that with your rudder brackets much higher I'm getting more rudder surface in the water then your are. Also do you have a picture showing how you did your pickup hole?

Dockman

Sorry I guess 7.5 mm difference ( your strut bracket is mounted lower on the transom then mine is). Ok what shall we figure out now?

PEERPSI

Yours are at 20, that would be 7.5mm. What's the distance of your rudder brackets from hull bottom, mine is 25 mm. It looks like mine was measured and setup in imperial as the bracket measurements would be 1/2" for the strut and 1" for the rudders. If your rudder brackets are at 40mm I'd guess yours was laid up in metric.

Someone was telling me that there were different length rudders coming from Aeromarine for the upgrade kit but I'm starting to think the issue is inconsistency in bracket mounting.

Dockman

I will try an get you a picture of the rudder tomorrow and post it. (The rudders are 148mm)

Dockman

My rudder brackets are around 36mm.