knotreel

You can take a look at a bunch of pictures on my website about the design and build, there are pictures of the bottom an a lot of other bs. Website is knotreel.com THe hull is Corecell foam cored has huge stringers and is about as strong and stiff as a brick. I have looked at it but never gave any defects any thought as the running surface is perfect as far as I can tell. Chines and all strakes still have sharp edges I didn't think much about the hull as it ran fine, no problem with the Optimaxs that I just removed. All this started with the new engines just installed a month ago. I will take a closer look though as anything is possible I guess.
The engines are set back from the transom 31" to the brackets and props are 47" back from transom.
I have been told the Suzuki likes to run deep but +1" set back 47" that is crazy. Maybe I should get some JB weld and redo the nose cones.
I have said the mercs and hull ran good before but all high speed stuff was done a goodly trim up, these zukes can't be even trimmed to level with the hull which is about 17% on the trim gage and I mostly run them at about 7-9% trim which is considerably under. Maybe the mercs would have got the bow lift pad too wet and lifted the stern if they could not be trimmed either. These are things that are bothering me and thinking maybe this maybe that, I have to just go down the bottom hole and re test then that issue will be done because no matter what I can't see me dropping below +1".

throttleup

Consider you added 200 lbs to the transom with the Suzuki motors compared to the 225 Opti's. You are going to need something to pick up the transom. Stern lifting props might work.

An easy way to test what's going on would be to add some weight to the bow. Try adding 50 lbs or so and see what happens, if handling improves add a little more. You also need to keep in mind the Suzuki props are turning lower rpm which is the reason most of the props for those motors are a larger diameter than what you would typically use for an outboard.

Just something to consider.

knotreel

Well thanks for all the sugestions, Bow lift stern, stern lift I really don't know? Thought i did but what I have decided to do is re-borrow the set of 14 1/4" X21P Turbo Ultima4's that I had on the boat with the merc's and briefly borrowed to made an offshore trip when my junk set of "break-in" props would not plane the boat. This was when the motors were in the fourth hole, up two holes from the present. They ran about as good as the props I have tested at the hole two. It will, I hope, be enlightening to see if they run at all speeds in hole two. If they do, then I guess I will have to have a set made from larger diameter props, probably the turbo offshore4's as these are available in their really cool "t-loc" hub that can not spin.
I am thinking these would be 23P.
So I will make that test later this week. Then if that fails i will go two the bottom hole and try some more.
This kind of stuff is what can happen when you build your own boat, very frustarting I will say.

ar300johnson

the first thing you need to do is take a long straight edge and verify that your bottom is still straight. do all the running surfaces, not just the pad. the next thing i would try would be a s blade prop that has both stern and bow lifting traits. i run a hydromotive 5 blade p 5x. generally the more blades, the less a boat will chine walk. from your handling experiences, it sounds like you need both stern and bow lift. hope this helps,

damdonzi

Pics from his site...

bbladesprops

I thought some one said this was a padded bottom. I don't see a pad on the bottom of this boat but I guess I could be missing something. Also the step/notched transom has a very small deviation from the bottom of the hull. I have seen this type of set up create handling issues. This could create a skiddish feeling at high speeds, kind of like riding on marbles.

I happen to have a RH and LH Fusion 4 in 23 pitch on my test shelf if you are interested.

Brett

knotreel

Sorry for not getting back but I was planning on some more testing before I came back.
About the bottom, it is dead straight. It is a 25.5 degree deadrise at transom and has a 16" wide keel pad that runs from stern up to where entry starts. This pad is 12 degree dead rise at the transom.
I was interested in the fusions as I was told that they were virtually the same as Ultima's. Here is what happened with my new "set". I ordered a 23 RH Ultima4 and picked up a 23 LH Fusion. I did this because Fusions are no longer made and Ultima4 is only available in RH in pitches above 21". So believing they had the same blade I got this "set". Well, they do run similarly up to a point but the blade shapes are not the same , the Fusion does not have the round ear design I wanted.
My latest two tests were a re-test on the 21P Turbo Ultima4's and the test of my new "wackly" set.
The Ultima's tested great with real good slip numbers that got better as speed increased in the upper ranges rather than worse as some of the others did. at mid range these got to 5% range and went in 4% range around 50mph.
Now I just tested my wackly set and these got down to 6% around 45 mph but got a little worse as speed went over this.
With a lot more seat time in the boat I now think I know what is going on. I believe the Suzuki's must be buried deep to run properly and my boat can not keep them buried as the boat rides up on the raised pad. The boat gets on the pad as you approach 50 mph and is really up over 50. My mercs loved this, my suzuki's hate this.
It is not chine walking, the port prop is coming loose and drive shifts to star and boat turns to port then the "s" curves are all me trying to correct. When the port comes loose the engine really doesn't always gain that much rpm, sometimes just a hundred or a little more. The nifty Suzuki syncronizers were fooling me earlier.
The Fusions that I though I wanted, I not too sure now as the lastest test where the fusion is on the port, indicated that the problem is worse than when two Ultima's are on the the motors.
So, I am dropping to the bottom hole and re-test. The Ventilation plate is now 2 1/4" up and going down to the bottom hole which will put me at 1 1/2" up.

After that some ideas I have are:

reverse the lower units to turn in
try some PTC4 power techs ( look like Ultimas in pictures?)
get a custom made LH prop to match the Ultima

My boat used to get to almost 60 mph with the 225 optimax's and now it's like trying to break the sound barrier which is about 50-51mph with the 300 zukes. This sucks!
BB, I might want to test the Fusions but more likely I think it will end up being a custom made Ultima4. I guess you could make one from a blank or maybe use a Turbo OffshoreI which would have plenty of extra blade to work with in cutting down plus have the T-loc hub?
Well first I have more work to do.
Thanks to all who have offered your advice. I don't think I am confused now but still looking to have that "ah ha" moment.
Ron
PS, my earlier conplaints of lack of responsiveness to trim and not able to trim out beyond level (19%) has been cured with the Ultima4"s .