Strut Angle and Placement

[WESTERNAERO]

Rigging pros, explain this to the masses please. Please have your explanations in three different categories. Flat bottoms, hydros and cruiser. Thanks for sharing.

[WESTERNAERO]

I guess I'll need to start. I've asked multiple people where the optimum placement for the strut needs to be on a Spectra/Howard cruiser bottom. Every answer I got was, between 20 and 23 inches from the transom to the end of the barrel. So where did that number come from? The only person that ever gave me an answer to that was Bob Teague. His formula is to place the end of the barrel 1 inch per foot off the transom.
So unless somebody can give a better rule, let's say that it the rule for strut placement on cruisers. How about angle? What's the rule?

Cruisers:
Rule #1. Placement/position = 1" per ft from transom to barrel end.

[2manymustangs]

I guess I'll need to start. I've asked multiple people where the optimum placement for the strut needs to be on a Spectra/Howard cruiser bottom. Every answer I got was, between 20 and 23 inches from the transom to the end of the barrel. So where did that number come from? The only person that ever gave me an answer to that was Bob Teague. His formula is to place the end of the barrel 1 inch per foot off the transom.
So unless somebody can give a better rule, let's say that it the rule for strut placement on cruisers. How about angle? What's the rule?

Cruisers:
Rule #1. Placement/position = 1" per ft from transom to barrel end.

Im going to throw something out here until someone that actually KNOWS happens onto this question... There have been plenty of threads on the other sites over the years where Rankin and others that are "in the know" have shared...

Seems to me that for any given hull design (flat or hydro) there is a time tested/proven sweet spot for the prop location depending on the strut angle/vdrive angle... The angle can and will radically change the way the boat acts, I will lets someone else talk to that...

As for the strut placement, that would depend on the TARGET prop location because you can only have so much prop shaft left between the strut barrel and the prop AND have the prop shaft survive...

SO you have to start with a known sweet spot/target prop location and work forward from there... The rig I saw for cutting the prop shaft hole was used AFTER the strut location was picked and the strut is in place... Then a prop shaft with a hole saw gizmo is used to follow the CENTERLINE of the barrel forward to the location where it intersects the bottom of the hull, the hole is cut and then you can start working toward the GEAR BOX placement...

With given angles of the strut and the gear box/vdrive there are going to be some basic dimensions that you will end up with once you pick either PROP LOCATIONS OR Engine location/angle... I don't know OR don't remember from past conversations but it is probably a compromise of engine placement but most importantly prop placement under the hull...

YOu don't want much prop shaft exposed between the front of the prop hub and the back end of the barrel...

Keep in mind that this ^^^ is for applications where you are putting enough load on the prop shaft to whip the shaft with tooooo much shaft exposed after the barrel... Which leads to prop placement, PROP placement under a performance boat is a HUGE factor in how the boat acts, even as little as .080 - .100 of adjustment in the prop locations fore and aft...

As I said, the sweet spot for prop location for a given hull is prolly more of a time tested/proven location than it is some kind of extrapolation any one thing... <<< speculation, im sure that the critics will have a field day with this...

[WESTERNAERO]

Thanks 2mm. If you noticed I started 4 threads, all in order from strut to engine as you would rig a boat. What you just said is what these threads need. Basic info to inform the masses. So how about some more detailed info on each thread discussing these items.
For example, what is the sweet spot strut placement and angle for a biesmeyer circle boat and why?

[wannabe]

WOW!!! Now you are really asking. Hydros, cruisers, runners and circles could not be any more different. So don't even relate them. They cannot be leaned upon.
Here is a start for your understanding. In a circle flat, you want to balance the boat at your "set" location. Meaning when the boat is "set" you want a balance that carries the nose, but also keeps the rear from dragging. This is completely dependent upon your power. So if you are building an SE style small block boat, you want your prop further under the boat as your difficulty will be not enough power to keep the nose of the boat suspended out of the water. The measurement we care about is front of propeller (rear of the strut) to the back of the cavitation plates. This is the most important number in any of the set up of a flatbottom. More important than engine placement, v-drive placement, driver, battery, etc.(yes, you can add longer cavitation plates to fool the boat into thinking that the strut is further under the boat than it really is.) As your power increases, you get to a sweet spot where the strut likes to be further back in the boat. Then at a point where your torque starts to increase above s typical pro-stock type of horsepower (650 torque, 850hp or so) then the flat actually starts to blow the tail of the boat, causing handling issues and problems to set the boat. (see k-boat power put in a ss type set-up) So you want to move the prop back under the boat again, to counteract that. (or just make longer plates) so the furthest back a strut wants to be is a good pro stock set-up. Then K boats and pump gas small blocks want actually really close to the same measurement. {if you can believe that} The angle of the propshaft to the bottom of the boat at the strut also determines how much the boat will lift out of the water. (Again, a steeper angle can get the boat out of the water, but you are trading upward momentum where if you are racing, you want all of the forward propulsion you can get.) This is why lake boats tend to be more angle than a competition racing boat. A typical super stock will want somewhere between 7.8 and 8.0 degrees of angle at the strut, from the bottom of the boat. Some have gone more shallow, or think that more shallow is O.K. as they have sufficient lift, and want to maximize forward thrust. When you start to creep up in horsepower and torque, you need less angle/lift to get the boat to ride happy. So many high power boats stay under the 8 degree number, when lake boats are regularly in the high 8degree to almost 9. You also have to figure that prop design will also effect this. More ear up front will cause nose lift, and leaning the prop ears back will settle the nose. We have seen boats with under 7.5 degree angles work, and at that point, much depends on the propeller. But boats under 7.5 tend to like only certain props. a good 7.8 or 8.0 will take just about any menkins you throw at it. You also look at how close the strut is the the bottom of the boat. But when it starts to get too close, you are really limited to a smaller diameter prop. But when you find the right prop, and your strut is shallow and close to the boat, that is when things start to really haul the mail. (see Dave Bryants ss91 boat)
So, never assume that a certain plate works for a certain boat. Or type, or class. Everything is the back of that strut to the plate. Take the K034 for instance. The strut is further underneath the boat, so it does not want long K style plates. Take the old SS33. The strut was so far under that boat, it almost did not want plates when it went to a SS format.
The most important thing to ask here, is; If you are going to set your own strut in a flat of any kind, make sure you know what power you are looking for, (lying to yourself and others at this point will be a real problem) and make sure you talk to those that know before you go and assume. Talk to the smart guys twice, then cut once.
When you place your v-drive - there is no magic number. It goes on the end of the prop shaft that is sitting in your strut. Just try and keep it down in the boat - so along the same axis of the prop shaft, but further back {making it down lower in the hull} and your total prop shaft shorter. Then tie off that v-drive with everything you have. As this is the location of all of the forward thrust of the boat.\
Was this too much?

[HotWater]

Good post wannabe! Lot's of info. I have measured 3 Biesemeyer's and 1 Revenge, each one had a different measurement. I guess each boat was rigged for a specific purpose or there was a lot of experimenting going on.

The K-034 team installed longer plates and some other bottom mods before the last race. Do you think the longer plates had something to do with the handling problems he was fighting?

[wannabe]

The K-034 team installed longer plates and some other bottom mods before the last race. Do you think the longer plates had something to do with the handling problems he was fighting?

Joey Cucci likes to run a standard revenge bottom (his mold) but put the strut further underneath the boat, then run shorter plates. (This keeps the standard measurement from strut barrel to plates the same) But if some don't know, they just see that this one k has shorter plates than the others. This fools lots of people. When you measure the barrel of the strut to the back of the plates, you will see that most boats in each class are so similar that it almost hurts.
Never let the plates fool you. Just like you don't let the placement of the v-drive fool you. It is all in the strut.
As for the 034, I would have made some of the bottom changes that they did make. But I don't know much about the plate change. I worried when I heard that they were making them longer, cuz I have run that boat before them, and knew some of what it liked. But they are smart, and knew what they were doing.

[Sharp shooter]

Rigging pros, explain this to the masses please. Please have your explanations in three different categories. Flat bottoms, hydros and cruiser. Thanks for sharing.

The problem here is that not all flatbottoms, hydros or cruisers are all the same. If you read wannabe's fine explanation above you have to consider that he's offering experience based on 1 particular type of hull design that being a Biesemeyer or the boats that's are copies of. It's likely that his info would carry successfully to some of the other types of hulls but maybe not with others.

There were a ton of manufacturers back in the day and it would be wrong to assume that every manufacturer took the time to perfect every model of boat that they laid up especially if you look back into the 60's and before. Some did, many did not. Those that took the time to perfect their boats generally only did so to their own factory race boats if they had any at all. A list of perfect set ups for every manufacturer and every different model of boat just doesn't exist. For conversations sake, if you bought a 1966 Tiger flatbottom tomorrow your best plan would be to find an identical boat that somebody else has already figured out and copy their set up. Otherwise, you'll have to do a lot of trial and error hopefully ending in success but there's no guarantee.

Some hulls like the Arizona Ski boats Biesemeyer (and all the copy cats- Revenge, D'Cucci etc) or most of the 70's 5/8th runnerbottoms do havea vague number of rigging measurements that get those boats close to if not dead on when it comes to making them work.

[gn7]

And NONE of this takes into consideration the prop design, that can lift the ass, drag the ass, or have the bow doing a moon shot.

How do you explain high wire walking? You don't. You take some pointers, get the basics, and then get your ass on the wire.
One thing is for sure. Both have the same requirements for success. BALANCE!!!!

This is like asking "what's the best BBC engine build" and leaving lie there. Who can, or even wants to attempt to answer that question.

All riggings are a compromise. Forward thrust verses bow lift. Lets face it, the IDEAL THRUST angle would be parallel to the bottom of the boat.

What we do toady, is nothing like what they did in the early 60s, but the boats and the POWER aren't the same either. What was IDEAL then, down right sucks with today. Even if you were to rig a 1968 Rayson LP, it would be different than what they did then. But its not they didn't know, they weren't playing with 800-1000 HP. Mike Wallace's U7 marathon boat had 425 HP. and weighed 2500 fueled, and half the fuel sat next to him, not next to or behind the engine. The boat had no lifting strakes, and no rocker. Try putting a 8 degree shaft in that and you have a submarine.

Westernaero, I understand why you started these threads, and its a cool and noble idea. The site needs SOMETHING to kick start some conversation outside the sandbox. This after all a boat site.
I think OG was COMPLETELY out of line in crashing Tish's train thread in a forum that is OPEN discussion, and maybe he needs to learn a little about how ANY site on ANY topic works. His BULLSHIT that RDP is ALL boat related is a total and complete farse. Anybody that has EVER visited that shit hole knows better.

However, I don't think you would go on a physics site and ask how hot is HOT, or a artist site and ask how blue is this?

The best you can do is exactly what YOU did, and ask, always keeping in mind, the more people you ask, the more answers you will get. One thing I learned long ago, ask 4 riggers what they think, and you get 5-6 opinions. Engine builders are even worse.
But each and every boat and its application is different.

[WESTERNAERO]

Bob you do know why I started these, you're correct. I'm not really asking for myself, but it would be nice to have a place to that's loaded with information that some young guy with his first v-drive could go and learn. You see it all the time on these forums. Some kid goes out and buys a 1968 Stevens, comes on the forums and says he going to put a 1000 HP in it, and then gets told by 10 different people it'll never work. No explanation as to why it won't work, no logical explanation how it should be, just a bunch of guys telling him "NO". So whats the kid do? Sells the boat and goes out and buys a jet boat or some wave maker.
These old vdrives are the hot rods of the water. If that same kid were to buy an old camaro and go on a hot rod forum and announce that he was going to 4-link the thing, he wouldn't get blasted by the members. He would have 10 people with good knowledge helping as much as they could.
Lets face it, the gentlemen "in the know" with rigging these things aren't getting any younger. So why not create a place that's filled with as much info as possible. Seriously how hard is it to explain this stuff, be it general rules that apply to most flattys or cruisers down to in-depth info on setting a beismeyer for SS class racing?
Thanks Wannabe, that was a nice little read.