new to RDP need setup help on a fast 25 step v bottom

[Apex svt]

Vastly different setup, but had a similar “Gray hound” hop once upon a time.

The center lifting strakes were cut smooth about 4ft forward of the notch to keep the stern planted. Along with a small diameter, low rake, radius ear props.

Enjoying the thread, a lot of great testing results. Best of luck.

 

[GregG]

Let us know if you ran the 6' straight edge along the bottom of the pad. If there is any daylight, that could help with next steps on the hop problem. How many inches below the pad is the gearcase bullet center again?

 

[25worldclass]

I have straight edged the bottom and there is a slight hook - 1/8" gap between the straight edge and boat bottom about 3 feet from transom from center of pad out to the first lifting strake. propshaft - gearcase centerline is 3.5 inches below pad with drive in neutral position

 

[25worldclass]

So far about 400 lbs in the back seat seems to be what it likes, but it scrubs off quite a bit of speed.

 

[GregG]

So far about 400 lbs in the back seat seems to be what it likes, but it scrubs off quite a bit of speed.

As you say, that is way too much weight to drag, but understand it helps the hop.

 

[GregG]

I have straight edged the bottom and there is a slight hook - 1/8" gap between the straight edge and boat bottom about 3 feet from transom from center of pad out to the first lifting strake. propshaft - gearcase centerline is 3.5 inches below pad with drive in neutral position

To ask for a bit more detail on the straight edge work. Are you saying you ran the straight edge on each side of the RAISED PAD only and that showed 1/8th at 3 feet?

 

[GregG]

Depending on exactly where there is a "hook" (or concave inward curve) it will act like a trim tab and push the bow down. Once the Warlock 25 pops up onto its pad and gains even more speed I'd bet there is only a few feet of wetted surface when running in a light ripple. Not sure if the hook is in the pad surface ONLY or in the hull next to the pad and if in the hull is the gap of 1/8" on both the left side of the pad and the right side.

 

[25worldclass]

The hook is in the pad surface out to and including the first strake on both sides of the pad then it seems to be fairly flat from there out. with a 6 foot straight edge it leaves about an 1/8 gap about 3' forward from transom very symmetrical on both sides of pad starting from center and working outwards. basically right where the boat is probably running most of the time when its touching the water I'm wondering if an extra half an inch of spacer and some prop work will overcome this ? I'm not at all a fiberglass guy and not sure who I could trust in havasu to fix the bottom properly. There seems to be a large community of hacks in this town doing crap work and its tough to sort through them. The last thing I want to do is have bottom work done by someone that does not know what they are doing. Also by reading I have heard of people having hook removed or other bottom work done and having major loose handling issues afterwards. A good friend in the fast boat industry has told me to be careful with bottom work, he said if you remove hook that is supposed to be there it can cause a bad porpoise and a very loose condition that will be hard to fix. But he is also not a bottom guy either so..........

 

[GregG]

That is good news. The hook as you describe it was meant to be there. Cross that off the list.

In addition to the cut Bravo, what other four blades have you tested?

 

[25worldclass]

I have 2 bravo 1 4 blades a non lab 30 and a merc lab 32 both cut barrels. I have not tried any other 4 blade props I have tried a few 5 blades merc maximus 5 blades, hydromotive 5 blades but the boat has always hated them. it lays over on the v and steers like an overloaded wheel barrow or a forklift at very high speeds. Very dangerous boat with a 5 blade. I was mainly just using them to determine the correct pitch after the whipple install

 

[GregG]

Throw a stock "Rev 4" on there to compare. As far as the drive depth of 3 1/2" below the pad, I would test a few props first before you move on the drive. As you already know, as you raise the drive to 2 1/2" you will pick up a little top speed but IMO you need to figure out the hop issue first by trying a couple of prop options. Too many variables at once make things confusing.

 

[25worldclass]

I believe the rev 4 is only available up to a 25 pitch.

 

[UltraLucky]

Might try a Bravo1 FS, bravo 1 without the flared hub. On my Hallett, straight V the Bravo 1 prop coupled with the standard length lower would create bow lift at speed and induce bow steer. Moving to a -2 lower helped along with the Bravo1FS prop. The shorter lower also limits the stern lift lessening the bow steer issues.

 

[GregG]

I believe the rev 4 is only available up to a 25 pitch.

You are correct on the smaller diameter. The new larger 15" diameter goes to 27 1/2 but with the blade area they act much bigger and the barrel is straight like the FS above.

 

[25worldclass]

How fast was your hallet my warlock did great with around 750 hp with the -2 lower on with a labbed and cup added to the tip of a 28 bravo 1 at 91 mph as soon as I added the whipple whole different story pitch wise I was running a 32 or a 34 with the -2 but anything above about 4000 rpm was almost un driveable the boat was downright scary constantly trying to go sideways and super ugly during deceleration until I put the 1.5 inch spacer in it then I went to a 30 or a 32 and it got way better but still takes a hell of a driver. Definitely not a boat that I could let just anyone drive

 

[25worldclass]

Hey guys sorry for the delays I took the boat out testing a few weeks ago and had a shift cable boot leak plus work has kept me busy. I spoke with a guy a few days ago who brought up a pretty good point. My hull was designed to run in the 70 to 90 mph range ballpark. Alot if not most guys running V bottoms up in the 100+ mph range are cutting the lower lifting strakes off the bottom about 4 feet forward of the transom to settle the stern. Does anyone know if they do this with step pad v bottoms as well? I'm still waiting to go to hill and have my props worked on and am not going to dive into bottom work just yet. I'm also going to step up to a set of 30" tabs when the season winds down. Last time out I tried running slightly less down on the tabs basically flat with slightly less up trim on the drive which helped with the stern lift but seemed to make the v bottom chine a little worse. Any thoughts ?

 

[GregG]

Hey guys sorry for the delays I took the boat out testing a few weeks ago and had a shift cable boot leak plus work has kept me busy. I spoke with a guy a few days ago who brought up a pretty good point. My hull was designed to run in the 70 to 90 mph range ballpark. Alot if not most guys running V bottoms up in the 100+ mph range are cutting the lower lifting strakes off the bottom about 4 feet forward of the transom to settle the stern. Does anyone know if they do this with step pad v bottoms as well? I'm still waiting to go to hill and have my props worked on and am not going to dive into bottom work just yet. I'm also going to step up to a set of 30" tabs when the season winds down. Last time out I tried running slightly less down on the tabs basically flat with slightly less up trim on the drive which helped with the stern lift but seemed to make the v bottom chine a little worse. Any thoughts ?

I do not agree with cutting the strakes. If the boat is up on the pad they barely play a roll at those speeds. Why are you chasing all the high dollar changes? Experiment with stock props on the try and buy programs that are offered first. For example, the Rev4 27.5 lifts the entire hull out of the water and runs like a much bigger wheel. Talk to Bblades about what you are trying to achieve, they are a wealth of knowledge on V hulls.

PS: Every hull is designed for a certain top speed until proper power and set-up blows right through that "limitation". Many examples so would take that with a grain of salt. There is no replacement for displacement.

 

[25worldclass]

My next step is definitely props. At this point I'm talking to everyone that has knowledge with these things to maybe see something that I am missing. Definitely not trying to chase high dollar changes as I am not a rich man at all. The boat definitely needs a new set of tabs but that will happen in the off season. Current tabs are shot and pretty loose in the pivot hinge they won't make another season without breaking. I was planning on talking to hill about my props and having the 30 worked on its an inexpensive thing to try and I have had good luck using them on quite a few props. They have always come back faster and better driving, except once and he told me that I wasn't going to get what I wanted from that prop but I told him to try it anyways since it was a free prop I had nothing to loose except the price of the lab job. He was correct it did exactly what he said it would. It was a lazy pig of a prop

 

[DarkHorseRacing]

Any chance switching to a cleaver style prop helps the ill handling? From the sound of it, it seems the blade area on the round ears is providing too much lift. Just a WAG.

 

[25worldclass]

I do have a #6 prop adapter and access to a bunch of cleavers that I could try but at 3.5 below my drive might be fairly deep for that type of wheel.

 

[25worldclass]

Also not sure how an sc lower would do running cleavers

 

[Blackmagic94]

Ever thought of slowing down in that hull lol?

 

[DarkHorseRacing]

I do have a #6 prop adapter and access to a bunch of cleavers that I could try but at 3.5 below my drive might be fairly deep for that type of wheel.

Shouldn’t make a real difference. We run a 6 drive deep and it’s got a cleaver prop on it.

I’d image the cleavers are easier on an SC drive as there’s less blade area than a round ear.

I think you should try it.

 

[25worldclass]

Hahaha not a snowballs chance in hell that I'm going to slow down.

 

[GregG]

You never know on props until you try them at those speeds

 

[Blackmagic94]

Hahaha not a snowballs chance in hell that I'm going to slow down.

I’m gonna be real with you. If you’re experiencing an instability that you keep chasing down and have not been able to fix on this hull then maybe it’s time to rethink this vs killing a family member or yourself.


Have you attended tres martins school?

 

[25worldclass]

I have not attended the Tre Martin school yet but it is in my future. I have a few people that we are trying to get set up to do his school. Just tough to get everyone lined up to do it. I have however been driving alot of fast boats for quite sometime. I completely realize that every hull has its limits and I understand the dangers of what I'm doing. That being said I am still pushing for better handling out of it. Everyone who rides in the boat is well informed on the dangers of what's going on. Actually when the boat has 4 adults aboard it is relatively mild mannered. Also rough water helps too. I'm just trying to get it dialed in for LOTTO next season. Smoother lazy water with one person aboard in a controlled environment. Not saying I don't drive it fast on the regular because that would be lying. I built the boat for the purpose of running some shootouts and surprising the crap out of the guys that think they have a fast single engine cat. Till they get drove around by a v bottom.

 

[Blackmagic94]

Tres can tell you what’s wrong with your boat when he drives it. Spend the money. You don’t need other boats lined up for him to fly to you.

 

[HST4ME]

1 you are out of hull and 2 the drive is way too low.
Point of the nose cone should be at least an inch above the pad and then you are going to have to find a really good prop guy.

When you are pulling water over the top of the cone it does all kinds of shit to handling. It tries to pull the back of the boat down and any positive trim makes it worse.

 

[25worldclass]

I wish it was pulling the back of the boat down. It's actually climbing the prop out of the water and viloently shoving the nose in on re-entry then the back tries to drive around the front. It was worse with 1.5 spacer removed. Moving the drive down actually made it more driveable. But I'm listening, I can get the drive to 2 inches below pad by removing it but it was awful when I started out like that when I first installed the whipple.

 

[25worldclass]

I do have an scx-4 that I could try with a ton of cleaver options

 

[Good Stuff]

I downloaded the video off instagram of his desert storm run so you guys can see what’s going on.

 

[GETBOATS]

Didn't read anything here about running a three blade, maybe I missed it. I not a stern drive guy, but the fast single outboards I've had didn't like cleavers or four blades. with the four blades, If I ran the boat in a slight right it was on rails, go left and not controllable above 95. Figured it was a transom lift problem and too much traction. Ended up running 32 three blade with lots of rake. long barrel brought the steering back also. Took a couple of years to finally get it, LOL but ran perfectly balanced after that.

 

[25worldclass]

unfortunatly that video is only like 70 at best and taken around half coarse the desert storm guys placed the video peeps in the wrong spot that was just a bad bounce with chine walk the real issue happens at the end of the runs ill see if i can get my lotto video from last year uploaded where it shows it nosing in

 

[HST4ME]

The past weekend up here this happened. I hope you are wearing the gear and the boat was set up with motor plates and not stock mounts.

 

[25worldclass]

I do have Lifeline comp race jackets for myself and passengers when running at high speeds. Also my boat has a solid mounted engine with a rail kit type plates on the stringers not factory adjustable merc mounts

 

[25worldclass]

 

[25worldclass]

this is a video from ozarks 2023 right after i installed the whipple. I had about a week of testing before heading to ozarks so i was only able to drive it 4800 rpm before it would get really stupid but i think this video shows the hop alot better. since then i have gotten the trim figured out better and can use more of the power but here you can see how it noses in

 

[25worldclass]

in the video i had the boat way under trimmed more trim helped but it still basically does the same thing. As it gets faster it starts to prop walk when the hull leaves the water and starts moving sideways..... crab walking.....

 

[25worldclass]

video was tabs neutral drive up a hair but not enough. after the trip i found that i thought i was trimmed higher than i really was more trim helped a little and allowed me to push it harder but it still does the same thing just at a faster speed

 

[25worldclass]

so far the only solution that I have found is 350 to 400 lbs in the back seat. That limits it to about 107 mph but it drives great. I would really like to get the handling without dragging the weight around and loosing 5 to 7 mph.

 

[poncho]

View attachment 1427555

All I can say is you got some big nuts, be safe...Looking forward to seeing how this progresses for you, I love learning new stuff.

 

[GregG]

Forget having people in the boat those speeds.

How big is the fuel tank on that thing?

 

[25worldclass]

80 gallons

 

[25worldclass]

The hop goes away with more weight. On my next time out a buddy and I are going to play with some lead shot bags in the rear corners and some trim settings trying to get it to take some sort of a set and hopefully get it to lay back on the tabs with them a little up higher

 

[25worldclass]

It drives best with about 3/4 to half a tank any less than half and it starts to get really flighty.

 

[Good Stuff]

The hop goes away with more weight. On my next time out a buddy and I are going to play with some lead shot bags in the rear corners and some trim settings trying to get it to take some sort of a set and hopefully get it to lay back on the tabs with them a little up higher

Have you tried trimming the tabs up out of the way since you added power? Watching the videos a couple of times makes me think the tabs are launching the stern out of the water. Doesn’t seem like the typical center of gravity porpoising where the bow is rising and falling with the whole running surface leaving the water like it is.

 

[25worldclass]

I have tried lifting the tabs but not recently, the boat has always liked a little bit of tab. That being said when I get a chance hopefully in the next few days I'm going to take it out and go through the trim and tabs starting from scratch. I have been thinking that I might be falling into old habits of what the boat used to like and just trying to drive through it. Generally from previous experience with this boat it chine walks constantly without some tab. also as I said before the tabs on this boat are hammered very loose in the hinges and cylinder pins so I will be putting new tabs on this offseason which will be 30 vs the current 24 so that may help also. I'm hoping the longer tab length will allow me to run less down tab but still provide side to side stability to reduce chine. I DO BELIEVE YOU ARE CORRECT ABOUT THE TABS PUSHING THE NOSE IN 100%

 

[GregG]

If your tabs have loose pivots that can be part of the problem. I still think the biggest part is you have not cycled through enough prop options, but loose pivots in the tabs get amplified A LOT at those higher speeds and can induce some hop. The video you posted was scary. It almost reminded me of a gas tank that was not properly baffled.

 

[25worldclass]

The boat drives better than that video now but still acts similar not quite as violent but still noses in. Some of that was me not being used to the new power and having it under trimmed.