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Discussion Starter · #1 · (Edited)
I have a 21' Dayruiser, and I'm going to have a strut built. The #'s on the current bronze strut are 212-10. I assume this is a 10 degree strut? I'd like to duplicate the current strut and not have to drill a new shaft hole, but if it is truly a 10 degree, I think I'll want to change the angle to 7.5 or 8, and thus drill a new hole.

Anyway, when mounting the new strut, how do you ensure the strut barrel is "parallel" to the stringers which are on the other side of the boat? My current thought was to have the mounting holes from the current strut duplicated onto the new one, which in theory would place it at the same relative centerline. Or is there a better way?

THanks
 

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By putting a new set of bearings (preferably not the fiber as those can often be a tiny bit off center) and a prop shaft in it you can get a pretty clear idea if the strut is properly placed by taking lots of measurements as you go along. My brother and I usually spend a day getting every measurement taken who knows how many times and using anything and everything to make sure it is perfectly where we want it.

Also, depending on the depth and angle of the strut you might be able to have a strut built that will still make it through the existing hole with just a little bit of elongation. Off the top of my head I would shoot for 8-8.5* of strut angle depending on the power. (That is a wild guess as I don’t know the hull at all). If you are running a 11.5” prop and you have an inch or more space between the hull and prop blade then you can tighten that distance up. Do you have a blast plate? If not then that would play into my plans.

Paul
 

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Discussion Starter · #3 ·
Thanks my hull is just a splash of a 21' 70s Howard, pretty bone stock all bronze hardware. It looks like the back of my strut barrel is only about 13" from the transom.. from what I've read this seems too far back? Also is there any magic in installing a blast plate?
Thanks
Mike
 

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Take Paul's advise here and spend more time than you need to on alignment and if you are going to the expense of a new strut and changing placement and angle the last thing you want to worry about is using the existing bolt holes.

I changed the strut angel and location on my Spectra but had the luxury of it being upside down to do all the work as well as route in a blast plate. Ill dig thru some picture and numbers and post them here, hope it will help. I got a lot of feedback from these sites to assist, VDriveCruiser on this site has a bad ass Howard with a lot of strut work done to it and he runs a lot of power.
 

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Hi Diamondracer, I have a 21 Howard that I've done a lot of work on. With the original strut it was fine until I got to the high 80's. It was down right squirely when i got into the 90's. I talked to Phil Bergeron,(RIP) and he advised me to change the strut angle to 7.5 deg. and move it forward until the rear of the strut barrel was 24" from the transom. He then made me a new strut, (which also moved the prop shaft closer to the bottom of the boat). This also meant I had to redrill the shaft hole and remount the V drive. This was some work, but well worth the trouble. The boat is now stable at 100 plus mph. I have also done some bottom blueprinting. If you have any more questions I will try to answer them. HPIM0734.jpg
 

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This us what we did on my Spectra 20.
  • Moved strut 8" forward setting it 23" off the transom to the end of the barrel. My Strut is a 9 degree, I ground into keel nearly an inch to get the strut where I wanted it and angled it a bit netting about 9 1/2 degrees, the angle and that half degree lined everything up real nice. I used a Strut that I had on the shelf, if you a having one made you wont have the same issues.
  • This allowed me to keep my gear box close to the original spot just a bit forward and lower in the boat and I did not have to re-drill the bottom for the shaft.
  • The other advantage having the gear box low in the boat is that you don't need a huge box to cover your drive shaft once you are done and running.
  • A 12” prop now is just under 7/8 of an inch from the bottom of the boat.
 

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Discussion Starter · #7 ·
Thanks guys those are nice rides. I still need to decide how far I want to go with this thing - one thing that isn't happening is flipping the boat over, so that may limit my options. One thing I'm really struggling with still is how to get the strut mounted straight. I know it is generally mounted before the shaft hole is drilled, so what is the point of reference for keeping it parallel to the stringers? Are most stringers somehow marked on the bottom of the boat or are there other reliable points of reference? Also I have a 12* Casale split case that I'd love to not have to swap out for a 10*, so I would probably like to keep my strut angle at 8 or 8.5 I think. My current prop when mounted has about 2" clearance or better from the bottom of the boat, so I'm hoping by tightening that up and decreasing the angle a bit, I'll still be able to use my existing hole (unless I decide to move the strut forward, which seems like what I should do).. I do have a close friend that runs a machine shop, so that should help.

Current motor is just a BBC 454 with a solid roller cam, 990 heads. Eventually I'd like to build a blower motor with perhaps a powerglide. Currently I just have a c72.

Mike
 

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I did not flip my boat to do this work, I just slid it back on the trailer and supported it. The base of my strut was made to fit the bottom of the boat, so that helped center it, also my boat had a centerline scribed on it. After locating the strut in the center and supporting it with a jack I pushed a prop shaft through it until it contacted the bottom of the boat and verified the shaft touched the center of the bottom. If not you should be able to move the strut slightly to help. Then I drilled a couple of holes and secured the strut to the bottom. After making sure everything was centered I drilled more holes and secured the strut and proceeded to drill a new shaft hole. You may need some help with this as it requires a special hole saw and a old prop shaft. Also in my case I had to add some new fiberglass in the original shaft hole because the new hole was going to be close to the original. Seems like a lot of work, but not that bad once you get into it, and very important if you are going to a blown engine. I can't overstate the improvement in the handling and speed in my boat. Oh and my propeller blade is about 5/8 to 3/4 inch from the bottom now and the V drive moved forward by about 13". Feel free to ask more questions if needed.
 

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Discussion Starter · #9 · (Edited)
I did not flip my boat to do this work, I just slid it back on the trailer and supported it. The base of my strut was made to fit the bottom of the boat, so that helped center it, also my boat had a centerline scribed on it. After locating the strut in the center and supporting it with a jack I pushed a prop shaft through it until it contacted the bottom of the boat and verified the shaft touched the center of the bottom. If not you should be able to move the strut slightly to help. Then I drilled a couple of holes and secured the strut to the bottom. After making sure everything was centered I drilled more holes and secured the strut and proceeded to drill a new shaft hole. You may need some help with this as it requires a special hole saw and a old prop shaft. Also in my case I had to add some new fiberglass in the original shaft hole because the new hole was going to be close to the original. Seems like a lot of work, but not that bad once you get into it, and very important if you are going to a blown engine. I can't overstate the improvement in the handling and speed in my boat. Oh and my propeller blade is about 5/8 to 3/4 inch from the bottom now and the V drive moved forward by about 13". Feel free to ask more questions if needed.
Thank you very much - I feel better knowing it is completely do-able without flipping the boat. Just a few more questions for the moment -

Does your strut have a V-shaped base and hull routered to fit, or is it flat & routered deeper with a flat spot ground out to support the flat strut ? (My current strut is v-shaped, and not recessed in the hull).
If I went with a 1" strut how large diameter hole should be drilled ?
Do you think I'll have a negative cruising impact with a setup like yours and not as much power ? (N/A 454) - like is there a down side to a shallow shaft angle like 7.5 ?
Is your v-drive roughly under your dash then ?

I'm actually still in the process of installing two new LVL stringers in this boat as the old ones were starting to rot from some dumbass leaving it out in the rain to collect water. I actually have a 2nd cruiser I'm going to sell to make more room for this project (it has 2 new LVL stringers as well). Maybe I'll look into obtaining a 10* v-drive.

Thanks
Mike
 

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My new strut has a v shaped base and is not routed into the bottom, it bolts on to the bottom,(you can also get a drop thru strut, but they are a little more complicated to mount). I could not find my hole saw, but the OD is 1 3/8" I believe for a 1" shaft. I have seen no negative effects at cruising speeds with this setup, 25/40 mph. V drive is right at the dash, about 106" from the transom. You should go to "Riverdaves Place" forum and look under "Boat restorations and upgrades" and then look at the thread titled "1988 Vector V drive". He talks bout moving his strut and shows a picture of his custom made hole saw as well as how he drilled the hole and many more good pictures.
 

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Discussion Starter · #11 ·
My new strut has a v shaped base and is not routed into the bottom, it bolts on to the bottom,(you can also get a drop thru strut, but they are a little more complicated to mount). I could not find my hole saw, but the OD is 1 3/8" I believe for a 1" shaft. I have seen no negative effects at cruising speeds with this setup, 25/40 mph. V drive is right at the dash, about 106" from the transom. You should go to "Riverdaves Place" forum and look under "Boat restorations and upgrades" and then look at the thread titled "1988 Vector V drive". He talks bout moving his strut and shows a picture of his custom made hole saw as well as how he drilled the hole and many more good pictures.
Thanks, very helpful. That other thread is great as well, thanks for that.

One more question about steering - how does your boat handle? Mine is kind of a tub. I have two short fins & the bolt for the first is at 81.5" from the transom. Any recommendations there would be greatly appreciated.
Thanks!

Mike
 

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My boat handles pretty well and will turn pretty hard if you push the speed up 60 or so mph. I only have 1 fin and since the boat is in storage right now, I don't know the exact distance from the transom.
 

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Mine will turn pretty good and 30 plus, I took her to a small river in Central Ca and was worried, because its tight, and I had no issues. My Strut is very close to where Mr Cruiser. (all these years and i don't know your first name) has his at, I extended the center lap strakes by 4' and really cleaned the chines up, wish I would have build them up a bit more. I also have a foot override on the plates and I bury it when turning hard and you can feel the boat move.
 

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Hey Cliff the name is Barry. What do you mean by "really clean the chines up". I never did extend my center strakes, I would like to but don't know if I have it in me at this point.
 

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Hey Cliff the name is Barry. What do you mean by "really clean the chines up". I never did extend my center strakes, I would like to but don't know if I have it in me at this point.
The chines on my Spectra were rolled over and chipped pretty bad, we added material and blocked them and put a sharp (er) edge on them. If you ever look at a schiada from the ass end you will see how pronounced and sharp their chines are as well as many new boats. I had a buddy who was trying to get me to add a lot of material, a couple of inches to the boat to really go after them. He had done a similar thing to a jet to v-drive transformation and the boat turned hard, but it wasn't a big o Spectra day cruiser :)
 

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Discussion Starter · #17 ·
Thanks for the input guys. I think I'm going to move my strut forward to about the 22-24" mark and have a new stainless 8* strut made (for my 12* casale). I'm running u-joints... hopefully the angle will work.

Mike
 
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