? for V-Drive Tom

[old rigger]

Tom,
I was hoping you might be able to explain something for me. You can file this under 'bonehead v-drive 101'. I might be the only student in class.
What effect does it have on a hull when it's set up using different struts with different degrees. I have a 21 Spectra waiting patiently in the wings for some work to be done on it. I've been told to run everything from a 14 to a 9 degree strut. Running a mild big block for power and only going to use it for family fun ( although I dont want to build a slug, and would like to run around 70) what happens to the handling or the performance of the boat when using the different struts? I know that most of the Schiada's I've cralwed under seem to run a 9, but most of these were set up for speed skiing when originaly built. Even if they are now just a river runner, there seems to be no adverse effects of running that angle.
The ironic thing, through the years of building boats, I only built 5 v-drives, at Howards, and they were the same bottom that the Spectra is. 3 were running blown motors and the others were more tame. I'll be damned if I can remember what strut was in them.
Even in flatties, a race set up, or just a family boat, what are the differences here. Is it something as simple as the bigger angles were old tech and all new stuff is set up using less?
thanks...old 'bonehead' rigger

[V-Drive Tom]

OLDRIGGER, This is a good one! It's going to take a few posts. To your last sentence first. Yes it is basicly the difference between old tech and new tech. New style fast daycruiser hulls are set up just thinking of them as over grown flatbottoms. The shallow angle with prop further under boat and v-drive much further forward, wants to pick up the whole boat.(7.5 strut angle, strut about 30 inches from end of cav plate, and v-drive up at about 103to105 inches from inside of transom.) These numbers will vary with different bottom designs. A STEEP shaft angle puts the boat on plane quickly, and shoves it across the water. (ie, tournament ski boats and old daycruisers are set up with steep strut angles. Tournament ski boats 14 degrees, old cruisers 9to12. You will notice some older daycruisers dont even need but two small fixed plates. Those boats will have steep angle and prop way back. That works great as long as you don't want to go faster than about 65MPH or so.) Same thing with old flats compared new runner bottoms.(old flats,9 degree angle,strut at about 22-24 inches from end of plate,v-drive at about 86 inches from inside of transom. New style runner bottms, 7.5 or 8 degree strut angle, end of strut barrel about 26 1/2 plus from end of plate and v-drive at about 96 or 98 inches from inside of transom.) As you know the runner bottom boats also have a rocker in the bottom to make them rock back and ride like they do. If you are going to modify an older daycruiser hull you want to be certian that it does not have any HOOK in the bottom at the transom or all these changes won't work. I think for a boat to have fun with and not a lake racer you can use 9 degrees with the strut barrel at about 26 or 28 inches from end of plate and v-drive up as far as looks right. There is so much more to say about this because different boats need different geometry. Well,now I hope I have helped. If any of this needs more explanation for anybody please ask! This is only the begining... http://free.***boat.net/ubb/cool.gif

[old rigger]

VD Tom,
Thank you for taking the time to answer, I know you are just scratching the surface of the subject. It's an art all it's own and you could fill volumes on how to set the hardware up right as well as what not to do. Great stuff.
When you give the measurments using a 9 strut for my cruiser, are you talking the trailing edge of the strut barrel to the trailing edge of the plates. I think you are, this makes sense to me, but I just want to make sure I understand you 100%. Even though I'm not going to be able to dump big HP into this Spectra, I'd certainly like to set up the hardware up to it's best advantage.
I have to flip the hull to recess the bottom for some plates, it was a jet, but the bottom is arrow straight and will require very little, if any work on it.
Thanks again.....keep it comming

[Kurtis500]

I got a ? for v-drive Tom. I may be off a bit, so excuse me if it sounds silly. I think you were at Firebird a few years ago and we got to talking about the races years ago. I said I remembered seeing Billy the Kid and the Silver Bullet running side by side. Funny thing was you told me the exact times and et's. Are you the same guy? http://free.***boat.net/ubb/biggrin.gif

[Costello]

Kurtis 500,
The Late Bill Todd was Tom's stepfather. I'm sure those runs are stuck in his memory like a tattoo.

[Kurtis500]

Yep, that was him.

[V-Drive Tom]

YES SIR, Mr.KURTIS500!! The experience gained from being involved with my stepfathers Billy The Kid hydros,(for me) is priceless! Those are my only Tattoos! Brain Tatts!
That was a big moment for us. It was the begining of that boat kicking bigass until he died in it Sept.20,1986 Castaic Lake.

[V-Drive Tom]

OLDRIGGER Yes sir, Tip of strut barrel to end of cav plate.(plate being 8 inches long) The 9 degree angle affords you the room for a large dia. prop. Shallow angle does not. (12 or 12/12) Don't recess strut much though, you want the Depth. TOM..

[Thunderbutt]

Old rigger, Does Tom know what he is talking about? You bet he does. I have a Spectra 20 and on the Spectra web site there was a guy that clamed his 20 foot Spectra would go 115 MPH I responded with a sarcastic statment ( sure it will if you droped it from a plane ) He came back at me and said just what Tom said about changing the strut angle and moving the v-drive forward. So now I beleave him. I would do the same thing to mine if I still lived in Ca. Do it, and good luck. luck. QUOTE]Originally posted by old rigger:
Tom,
I was hoping you might be able to explain something for me. You can file this under 'bonehead v-drive 101'. I might be the only student in class.
What effect does it have on a hull when it's set up using different struts with different degrees. I have a 21 Spectra waiting patiently in the wings for some work to be done on it. I've been told to run everything from a 14 to a 9 degree strut. Running a mild big block for power and only going to use it for family fun ( although I dont want to build a slug, and would like to run around 70) what happens to the handling or the performance of the boat when using the different struts? I know that most of the Schiada's I've cralwed under seem to run a 9, but most of these were set up for speed skiing when originaly built. Even if they are now just a river runner, there seems to be no adverse effects of running that angle.
The ironic thing, through the years of building boats, I only built 5 v-drives, at Howards, and they were the same bottom that the Spectra is. 3 were running blown motors and the others were more tame. I'll be damned if I can remember what strut was in them.
Even in flatties, a race set up, or just a family boat, what are the differences here. Is it something as simple as the bigger angles were old tech and all new stuff is set up using less?
thanks...old 'bonehead' rigger [/QUOTE]

[old rigger]

Thanks Tom.
Thunderbutt,
I agree with you about Tom. We're very lucky to have someone like him that has the experence, and is willing to share it with us. I got lot's of dumb questions when it comes to v-drives, and plan to ask for more help here when I begin of the 21.
About that Spectra, mine will never aproach those speeds, 115, but I'll tell you what, you drop it off a tall building, you won't hurt the thing when it lands. The lay-up is second to none on this hull, that's the main reason why I bought the it. (that and it was already on a v-drive trailer) I was only half heartedly looking for a project when this came along, and even though it was a jet hull that had to be converted, I'm still $$$$$ ahead doing it this way. The glass work is first rate.

[smalls]

T-BUTT,
I have never gotten any bad advice from Tom. He is always been right on.

[smalls]

Originally posted by smalls:
T-BUTT,
I have never gotten any bad advice from Tom. He has always been right on.

[VD CRUISER]

FYI, From personal experience, my 21'1983 Howard, (21 Spectra), came came with a 9 deg. strut mounted 17" from transom,(27" from end of cav. plate) and handled pretty well with an unblown 454, 83 mph and a fair amount of porpoise. As the HP went up it got tricky, more porpoise and some chine walk. With the current blown 547ci it got into the mid 90's but was lifting the transom and feeling squirrley. When a propeller blade came off and just about jerked the strut off the bottom and fractured the glass around it, I decided to make some changes. After much disscusion I had Phill Bergeron make me a 7.5 deg strut and I mounted it with the end of the barrel 23.5" from the transom,(33.5" from end of cav plate). The V-drive centerline came in at 110" from from the inside of the transom. I have now seen 109mph and no chine walk. I love the way it handles, it just carries the nose like a flat. I run 48% overdrive and turn the motor about 6200 rpm with a 11 1/4 x 16 or a 12 x 16 2 blade. I did do some bottom blueprinting to get some hook, that was under the cav plate, out. I don't see any ill effects at slower speeds. I don't know my exact HP but it should be close to 925/950. You might want to consider a set up something like this in case you want to add more power later, and it doesn't cost anymore. Just my .02. Like Tom said there are a lot of things to consider and I'm sure there are many ways that will work. Keep us posted as to what you come up with.

[old rigger]

VD, thanks for the info.
Sounds like you really have you Howard dialed in.
When you were still running the 9 strut, did it porpoise at lower speeds as well, you know cruising at 30, 40 or 50. Or did it happen just when you were on the gas on top end? I ask because I know that unless I hit the lottery , I'm never gonna have the scratch to run a motor that's putting out close to 1000hp. I'm not complaning, I just know what I can afford (and what I can justify to my wife). 400 to 500 is more realistic for me. My buddy has a PlaceCraft thats about 10 years old, it's an outboard which is a whole different ball game, but the way he's set it up, it's fast but it never stops porpoising, at any crusing speed. What a miserable thing to spend your weekends in. I want to avoid ending up with the same problems. I/O's, Jets and outboards, I can figure out, but I really appreciate the input from you v-drive veterans that have been down this road (river) before.

[Costello]

Old Rigger,
I have an older 9 or 10 degree strut in my 21 Di Marco. It's running right about 60 mph right now, but very very smooth. It likes the chop which frees the boat up quite a bit. It is quite "stuck" in smooth water. I am going to get the prop under the boat a little further to free it up under smoother conditions. I don't have all of my dimensions, I've been too busy just getting it all back together, but when I get them I'll post them as an example of the way the older style deal is set up in contrast to the info Tom and VD Cruiser posted regarding the setups that handle better at high speeds. At least with my deal there is no porpoise whatsoever, you're right that porpoising would make any boat a miseraable POS.

[superdave013]

I had a 9 degree on my 20' and it was running in the mid 80's. On the big end if you pulled the plates up is would feel pretty loose. Not scary but you could tell it was riding pretty high. It did not porpoise at any speed no matter what the plate postion was.
Now I am at the point in the project where I have to decide if I should keep the strut or go with a lower angle drop thru. I am being urged buy others to change it with the HP increase. That most likly would require a longer propshaft I think. So this thread is of great intrest to me.

[Thunderbutt]

Dave, my Spectra has a 9% angle and at 6200 rpm you better be hanging on and praying. put the plate down and no problem but your pushing a lot of water, and no speed. Originally posted by superdave013:
I had a 9 degree on my 20' and it was running in the mid 80's. On the big end if you pulled the plates up is would feel pretty loose. Not scary but you could tell it was riding pretty high. It did not porpoise at any speed no matter what the plate postion was.
Now I am at the point in the project where I have to decide if I should keep the strut or go with a lower angle drop thru. I am being urged buy others to change it with the HP increase. That most likly would require a longer propshaft I think. So this thread is of great intrest to me.

[Costello]

I had to crawl under the trailer today anyhow, and I took a tape measure with me as I stated above. I have a 10 degree strut, in at 28 1/2" off of the transom to the strut barrel. The motor is only at 24 1/2" off the outside edge of the transom. V-drive is in at 102" from the outside edge of the transom. The prop shaft is 78 1/4". It probably only needs to be 77 1/2" and then play with it from there. It's too far off of the strut barrel, and the boat is glued in when the water is smooth. Just another reference point for anyone that may be curious. If Tom or anyone else wants to throw out a few pointers with this setup, I'm all eyes. http://free.***boat.net/ubb/smile.gif

[Backfire]

The subject of hardware placement, comparison, and characteristics has come up before, and I'm intrigued by it enough to reccommend this info to AzDon for permanent placement at his website (since he is one of my multiple personalities, I think I have some influence with him!)

[V-Drive Tom]

Costello,
Measure everthing on the inside of the boat from inside of transom.(tape measure butted up against transom to first motor plate, then from inside of transom to v-drive plate.) Everything under boat will be from end of cav. plate. (unless there is no plate or you want to mention how much of it is plate,ie,strut barrel is 281/2 inches under the boat with 8 inches of plate.)
I agree with moving the prop forward on your boat. The way you describe the boats attitude, it may help. Once any boats combination gets close then the tip of the propeller blade to the end of cav. plate is the demention that will matter. The strut barrel is just the first reference point. Im glad to here you have had the boat out and are having fun!

[Costello]

Tom, when I get another dirty shirt on (yesterday I had an old Menkens shirt on http://free.***boat.net/ubb/smile.gif) I'll get back under there. Roughly I have 9 1/2" of transom from outside to inside, so V-drive would be at 92 1/2" and motor at 15".

[VD CRUISER]

Old Rigger, With the 9 deg strut the boat would run smooth without porpoise at most any speed if you kept the plate down. When we let her go we would always raise the plate and let her fly. With the plate up it would porpoise and it was faster and more fun. It will porpoise with the current set up if you take off hard with the plate up, but it seems to level off at the top end, or you can take off with some down plate and avoid porpoising.
Superdave, you're putting a turbo motor in it aren't you. I think you would really like the way it will run if you lay the angle down and move everthing forward,and yes when you lay the angle down the prop shaft will be longer. I didn't mention it before, but when I went to the blown 547 and still had the 9 deg strut, the boat would stick to the water at top end, and I couldn't get it to free up, plus it was beginning to bow steer. I guess I'm lucky it didn't swap ends with me. Tom mentioned 8" long plates, mine are 10" long, but I don't know what difference that makes. Also my strut barrel is closer to the bottom of the boat now and a 12" dia. prop only clears the bottom by about 1/2 of an inch. Bergeron seemed to like the prop close to the bottom.

[V-Drive Tom]

VDCRUISER,
When I mentioned wanting the strut depth on oldriggers boat it was because of what he said he wants to do with the boat.(halling people,pulling kids,and lower power)
That way he is not limited to a 12 inch prop.
Most plates are 8 to 9 inches out of the boat. Ten inches is fine too. When I am giving these numbers in conversation they are general numbers for what that person says they want to acomplish, with what they have. I fully believe your boat kicks ass, but I think a guy could get in trouble moving everthing that far forward in some of these other hulls. http://free.***boat.net/ubb/smile.gif

[VD CRUISER]

Tom, you're probably right. When I was doing this deal I was told two different dimensions on mounting the strut, so I sorta split the difference. Also no one seemed to know how much was too much, and what would happen if I did put it too far forward. Could you comment on that? When I was trying to get it to run with the 9 deg. we kept trying smaller dia props to eliminate tail lift. Now it handles about the same on the top end with the 11 1/4 dia prop as it does with the 12" dia. Of course it takes of better with the 12". What dia and pitch do you think would work best ?

[V-Drive Tom]

VD Cruiser,
I don't know how far is too far. Any boat larger than 21or22 feet, I don't know much, or care about. I would be nervous telling anybody to go any further forward then you did on your boat. Phil Bergeron is a very good source for set-up on those boats.
I would always use the largest dia. prop that I felt the boat and engine can handle. Is your 12 inch prop a 2-blade or 3.
As for pitch I would not run more than 16.

[Thunderbutt]

Tom, I have a 20 Spectra. How do I tell what angle the strut or v-drive is? I have a Champion ( sorry Tom). My strut is 24 inches from the plate and the v-drive is 91 inches from the transom and real close to the bulkhead. Right now I have a 13/16 prop on the boat and I have one and a half inches to the bottom. Originally posted by V-Drive Tom:
VD Cruiser,
I don't know how far is too far. Any boat larger than 21or22 feet, I don't know much, or care about. I would be nervous telling anybody to go any further forward then you did on your boat. Phil Bergeron is a very good source for set-up on those boats.
I would always use the largest dia. prop that I felt the boat and engine can handle. Is your 12 inch prop a 2-blade or 3.
As for pitch I would not run more than 16.

[V-Drive Tom]

Thunderbutt,
The easy way is to get hold of a digital level.(about 6 inches long,$150.00) You can also use a leveling protractor. You will compare the angle of the strut barrel to the bottom of the boat. I will guess yours is 10 degrees plus. I will also guess that your v-drive gears are 4% overdrive.(lots of champions came that way. Plus the size of your prop 13-16 tells me you needed all the prop you can get to hold your motor down.) Struts are normaly stamped with the degree, but Im sure you have already looked for that. http://free.***boat.net/ubb/biggrin.gif

[VD CRUISER]

Thanks Tom, My 12" was a 2 blade. I sold it and was thinking of trying a 11 3/4 dia 2 blade. The boat just seems to take a little better set with the smaller dia. What is your opinion on Blade area ? Do you like small or large blades ?

[V-Drive Tom]

VD Cruiser,
On a set-up like yours I would like more blade area and high blade rake,like 14 degrees. A wider blade area makes it easier to have more pitch progression, like from 14 to 19. 14 on leading edge ,working up to 19 plus on the trailing edge. Those three things will help the two blade grab harder at the bottom. Although a true pitch type prop(with little or no progression across the blade(16) would take off more slippery but produce a higher MPH on top.)
If you would call me, I may be able to have a custom profile shaped for you to try.
I get the feeling you wouldn't mind being a test mule! http://free.***boat.net/ubb/cool.gif

[PGF545]

Tom, thanks for calling me back on the prop. I talked to Randy yesterday and he said that he wants to get one from you. I told him that if I went to the next race in June he could borrow the one that I have and he could see if he liked it. From what he was telling me I think that the one that you have will be excellent for his combination. The one that he has now is doing about the same thing that the Menkens one that I have was doing on our boat. Thanks again for the help and maybe he will call you soon.
Bernie