Another BFN Rebuild

I love the blue. Gonna be a head turner for sure. Might get wiplash!

Dad continues to chip away at rebuilding the platform- it was pretty rough as well as loose, plus it had some sort of coating (varnish?) that did not come out when we used the teak cleaner on it... so it was completely disassembled, each individual piece sanded, and now it is being put back together. By the time the sanding was complete, almost 3/8" was taken off the length (front to back). We're also using larger (but shorter) screws- I believe #10 1-1/4", in hopes we wont have any tips protuding through the top side, which had been a problem. Once complete, Ill snap some pics.

The tranny is off, and the new damper goes on today or tomorrow... it looks like the one on there now was original, as it still has some OMC green overspray on it.

In the meantime, we've made some progress with the carpet.

Sides trimmed:





Floor test fit:





Floor glued and rolled:





Floor trimmed:







I also organized the garage somewhat and found our carpet trim.    I need to clean it up with acetone and cut it down to length- then it can be put on the carpet and the last bit of the floor can be glued down. The final pieces that go over the pockets will get done last. I'm using the same method for the carpet as I used on my '90, which I described in this thread. The only difference this time is that we're using a dedicated carpet knife instead of a utility knife. Changing the blades often is key! Watch out though, those suckers are sharp.

Thanks Seb. The only thing we've had luck "scheduling" up to this point is time to work on the boat... and even that has been hard to do at times! Every time I think our water test will happen by a certain date, it hasnt happened- so I refuse to even speculate!

It is looking very good gentlemen. About 2 weeks to the offical start of watersports season.. 7 weeks till the end of project season... bang that sucker out and lets go skiing.

Craig, I sure hope not! Maybe though.

Joe, good call- the final push is going on right now... once the warm weather hits, Im not a big fan of spending all my free time in the garage!

lfskizzer wrote: I just cant wait to see it in the water

Thanks Phil- me neither!

Over the last few weeks, Dad took a vacation to FL and Ive been traveling a bit for work... but we're still chipping away!

We dropped the engine back in the boat.



Then we centered the mounts and positioned it on the cradle tabs until we were satisfied with where it sat. Then we aligned it. Then we drilled the holes in our tabs and bolted the engine down. Double checked alignment one more time. We then inspected our shaft/strut/prop/rudder position... we decided to shorten our shaft 1.5" to bring the prop within 3/8" of the strut body.



Once we got the shaft back, we reinstalled it in the boat, along with an OJ dripless shaft seal.



Despite moving our pylon forward ~2", and moving the engine back approximately 1/2", we're still tight on clearance between the floor and RWP... but we made it!



Today we finished mounting the transom pieces- pitots, trim, fuel tank vent, bilge pump fittings:



We also mounted the rear panel support brackets. Fuel tank brackets are back on as well.



And just for Joel... the dorky steering wheel that came with the boat when we bought it is finally off. We'll be replacing it with a proper 3-spoke one.

TRBenj,

I have been keeping up with this thread but I have to admit I have not read every word of every post. So I have to ask, what will be the benefit of shortening the prop shaft?

By the way, very nice job on the restoration! being a helicopter mechanic, I have really enjoyed the technical aspect of the entire restoration.

Matt

Dieseldawg wrote: I have to ask, what will be the benefit of shortening the prop shaft?

The less shaft length you have hanging out past the end of the strut, the less stress will be put on the shaft. Also, bringing the prop forward will improve performance- it will raise the bow a bit at speed. It will also increase prop to rudder clearance... all good things. Basically, you only want the prop far enough away from the strut to be able to get a puller on. 1/4" would have done it, but we left a touch more in case other props fit on the taper slightly different.

The only downside is that bringing the prop forward decreases prop to hull clearance. We have just under an inch (~3/4") now, which while better than the factory had it (~3/8"), is still a bit less than the 10% of the prop diameter rule. We'll keep an eye on the keel and see it starts showing signs of damage again. If it does, we can either put a metal plate on there, or remove the 5/8" of material aft of the strut like the '81+ BFN hulls had.

Pete,
If everything is aligned correctly shouldn't the thrust be directly in-line with the shaft???
If so it shouldn't put any leverage on the strut or the strut bearing, if it applied leverage wouldn't that wear the strut rather quickly??

8122pbrainard wrote: TRBenj wrote: Dieseldawg wrote: I have to ask, what will be the benefit of shortening the prop shaft? The less shaft length you have hanging out past the end of the strut, the less stress will be put on the shaft. And the cutlass bearing. Matt, As a mechanic, you should know this. In mechanical engineering terms, it's called "overhung load"!    A basic principle of physics and the use of a lever.

Pete,
I do understand the principles of overhung load as I deal with it every time I track and balance a rotor system on a helicopter. However; my understanding of overhung load is far less than yours due to the fact that I am just a mechanic and not a well versed engineer. <-----That was not meant to be a shot across the bow. I am just stating my intellectual limitations.

I do see the reason for the shorter prop shaft in this application, given the high HP and Torque loads. I guess in this case I just was wondering what would be the end result in performance (speed and drive-ability) after shortening the prop shaft. The wealth of knowledge, information and expertise on this site is just flat out AWESOME!

TRBenj,
Would a tunnel in the hull work if the propeller clearance becomes an issue? Similar to the tunnel on any of the 196 or 200 ski nautiques (minus the hook). And if you were to make a tunnel in the bottom of the hull could you lower the engine and reduce the angle of the prop shaft? Although that sounds like a whole bunch of work!

Matt

Matt, a tunnel wouldn’t work that great on this v-hull. The keel is too narrow- its only 3-4” wide. The TSC2 and TSC3 196/206 with that design feature have much wider (6”+) keels. If prop clearance becomes an issue, we can notch the keel aft of the strut, as discussed here:

Keel Modification

We added fiberglass to the inside of the hull in this location, just in case we wanted to make this modification later on. Only the first 2 years of the BFN (79-80) didn’t get the notched keel- all 81-90 BFN’s had it. This allowed them to run 14x14 props, whereas our boat originally had a 13x15.



As far as altering shaft angle, a simple hull clearancing near the prop wouldn’t help this. That would require a strut and shaft log change, at a minimum. The BBC and 72C tranny are already within ½” of the hull, so theres no room to be gained there either.

Jeff, Mastercraft did the same as CC on their hulls to accommodate the 14x18 prop they ran with their 1.5:1 Powerslot transmission. It only looked special on those boats because the hull was otherwise flat. To my knowledge, it was only a prop clearance modification- not a wake shaping one like the TSC2+ 196. The 86+ PS190 hull did not have this notch, despite having the same ‘slot tranny offered… they got a little smarter and designed the hull and shaft/strut/prop geometry to accommodate the larger prop without a tunnel.

Oh, and FYI, theres no such thing as “centrifugal force”.

Tim,
Haven't read thread in awhile, that thing is looking sweet! Nice work by you and your dad!

sandbagging sonofabitch