KNOT-RIGHT

All good suggestions...Thanks for all the ideas and comments guys.


Gerry

OLD MAN

Artie, Talked to Gerry today and we both agree that not enough
of your back end is staying in the water causing the boat to have
the porpoise effect. I think the fact your box is putting the drive
so far away from the transom, this is more than likely the cause
of it all especially on a 28' boat. The drive should be tucked
closer to transom but you can't do that now. I would say that
Wieland 77 has the least expensive solution to your problem...
add a 2 to 4" shortie to your drive. This will bury the prop down
far enough so you can run your tabs flat with the bottom. You
should have enough weight with your package to keep the ass
end down. OK! George

hotjava66

Hope things work out, these are great boats when they are dialed in. Lots of good suggestions. Its kind of tough with a limited number of boats out there because not a lot has been tried. I just noticed that the Konrad has some extension built in, that may be an issue as stated above. I seem to remember someone, may have been Doug, saying the 28's didnt react well to extension boxes. I could be wrong but may be worth checking with him and finding out. Personally, I would try a few more props first, maybe a Bravo 1 30 and a Mirage 29 if you can lay hands on them. Then a standard lower or more spacers. Another thought, I dont have any experience with 5 blade props but arent they made to run nearly surfaced? Maybe your current setup is too deep for a 5 blade and too shallow for a 4 or 3?

littledcsrodshop

iTrader: (1)

Sorry I was thinking he bought his Ace set-up from "Elite Marine" Kirk who parted out his 28 Pantera with big power & an Ace a while back.. I think he's out of Il

Hey atleast I was close !!

I'd be curious to know exactly how much rocker Artie's boat has with a good straight edge on it, and exactly where it starts..?? I have no idea if there were any bottom mods. on these hulls from the 1st hull to the last.. ?? Also if the singles & twins had the same amount of rocker in them ?? I know my hull has a touch of rocker, but I've never measured exactly how much... I'd be glad to check it for you guys in the next day or two if it would help ?

Dan Adams

Thanks KR. This is what my drives look like all in. It will drive the nose in hard like that. Porpoise is speed sensitive for me. With the boat being able to handle more trim and less tab above 65. It really starts to get happy at 85, at 95 and up she is in her glory.
I'm with Mike W. and George on the deeper theory, sure worth a try. The lack of neg. trim might be ok then. Kind of a different scale, compared to the Fountain, Arties looks like a plus 1 1/2 at full in.

marinetrans

its most likely da "box" boxes make hulls do funny things some times, if you keep the box, the bottom of the boat may have to be extended with "running plates/extension pieces", like they did on TKO/Sutphen

AIR TIME

yow Pete thanks for the input. I recall your hull didn't like it. but the 24ol and 25ol baja hulls do oh and AT25. the 25/27 baja sports do not. I hope its not the box. KONRAD DRIVES is sending me a reg lower hp. that will give almost 2'' from where I started. plus I should take mine out one more time with a trans lifting prop and try the 380 k planes at neutral. then try the reg lower and can add the spacer too. but I hope its not that much. I need to run it above 60 to see if it gets better. now I am told this hull porpoises between 30 and 50, but goes away with tabs down. I never ran them down last weekend.. I was pissed with the carbs and starter. so sunday or wens I'll go out with more props lowers tools. hope for the best. Idon't get why some boat companies put rocker or hook in there boats. I believe sutphens are just straight vee's and thats why they run high x and are fast in any water. I won't chase this next year, I'll strip it and sell it like I bought it, and it has a new gas tank. I'll look for a 26 or 31 sut, drop my chit in. also when we turn this hull leans way over.I could use tab but its a pain. more pics coming got to down load them 1st. bring a life line and helmuthooking up a kill switch and going to see if the porpoise goes away over 60, I plan to run 5000rpm at some point for # for bret at bblades he needs a hard run to see slip#. later Art

AIR TIME

hey thanks, I think a 3 blade is a no no when a 4 blade was slipping. the cupped 5 grabs best. the full lower will put me at 4 3/4'' below the keel and I could add the spacer, I hope not. then I would be over 5 1/2'' deep .

AIR TIME

we have a 13degree trans, with my box its 14 degrees. konrad doesn't think its the angle its drive height or too much weight out back. and I just spent 1400 plus on the new tank and thought about putting it in the floor with the weight out back. I just want to be able to control the porpoise at low speeds. I do need a run over 60 to see if it goes away. how is yours coming, if you didn't cut your x out I would set it at 16 1/2 = 4 1/2'' or 5'' with your its box. or wait and see where I end up. you don't have atrany and your drive is lighter than mine, b ut that konrad looks mean back thereart

Audiofn

I looked at my Donzi with a TRS on it and it trims down about the same as what I am looking at with Arti's picture. Arts picture looks a little bit like the bow may be down a bit? At any rate you are not going to run at speed with it unless it is trimmed up so IMO this is a non issue because you would run nutral or possitive trim at speed. Both my Donzi and Formula have rocker. My buddies Formula (same exact boat as mine) is a porpoising mess were mine is not. 311's have rocker in them as do 302's as well as Donzi's. IMO there is a HUGE CG issue with these things. I don't think it is the drive, they are porpoising messes with Bravo's so.... Got to get to the bottom of the issue. IMO you will find to much weight up high and to far to the back of the boat. So the question becomes bandaid fix it by adding longer tabs, or some other fix like bags in the bow, or get to the bottom of the issue and start to look at the CG's.