Another BFN Rebuild

Things are starting to slow down a bit here with winter having set in and the holidays upon us... so hopefully this will spark a bit of interest. There have been several worthy BFN rebuild threads (Buffalo, Hasbeen, Grinch), but ours will have a few unique elements- so while I was initially hesitant to start a thread of our own, I guess theres no harm in doing so. So here goes- you might want to put on your reading glasses though.

A bit of background: This past summer I was able to convince my dad that a BFN would be a nice addition to our fleet. We found this '79 in New Hampshire, and while it was a little rough around the edges, it was largely complete. While I wouldnt call its performance during the test drive overly impressive (it was taking on water at a pretty good clip, it wouldnt come out of the hole to save its life, and one of the speedos leaked all over me the whole time), it did turn in an honest 52mph on the GPS- so we were sold. Over the last remaining months of summer, we tinkered with it a bit- tried a few props, added a DUI distributor and a 750cfm Holley, did a bit of rewiring and gauge replacement, put on a new starter, re-sealed the rudder port (and got a new rudder when we didnt safety wire the original back on), etc. We footed with it some and hot lapped the lake a bunch. It was reliable, the holeshot was much improved, and it turned in a best of 58.5mph in Lake George to win the 2009 "Adirondack Dash"... so not bad first summer.



What we knew going in was that any boat this age was going to need structural work at some point... and while all the motor mount lags were tight, the boat did come without a cover so it had been exposed to its fair share of weather. The only soft spots in the floor were in the rear removable panel and a little bit around the pylon- but we figured it was due sooner rather than later. The glass over the stringers in back had plenty of cracks as well. When we pulled the pylon out of its cup in the hull when using the boom (the floor flexed enough to allow this), that confirmed it... this winter it would get re-strung.

So this is where the fun part begins. Dad has done most (all) of the hard work up to this point- having the boat in his garage makes it a bit easier, I suppose. He pulled the floor to find most of the wood to be rotten, no doubt helped along by a lot of waterlogged foam. The front section between the engine and bow were particularly soaked- the 3 vent hoses which had disintigrated and the faulty battery box drain were surely contributors. Dad said he easily removed 400 or so lbs of foam. These are the only decent pictures I have up to this point, along with the ones I shared in the "redneck engine hoist" thread:






With the weight of the 454 and soaked foam gone, the trailer springs have breathed a sigh of relief!

As it sits now, all of the stucture has been removed, save for one main stringer. Ive got a bit of grinding to do this weekend, and then it gets tucked into the back of the garage where we will start to put it back together.

We've assembled a list of modifications and changes we want to make. These include:

-replace all wood in floor and stringers with composite
-install engine cradle
-replace all flimsy vent tubes and hoses with PVC pipe
-move pylon 2" forward to allow access to bilge in front of engine
-install kick plate that spans half the width (like on newer boats) for more under bow storage
-replace drivers seat frame with 80-84 (non-delux) version to allow easier adjustment

We've also got some engine work planned and some cosmetic work to do, but Ill save those for another thread.

Right now, the plan is to not refoam, at least not entirely. We may do a bit of the bow section to give the boat some floatation and hold all of our tubes/vents in place. Thanks to JoeinNY for that idea. Im also stealing a page from Joe's book with the stringer and floor material selection- Coosa. He's been a great help so far by cluing me in on some of the finer points of his construction.

Before we start ordering materials, we're going to mock up all the pieces we'll need out of wood. That should give us an accurate idea of how much we'll need to buy. Probably a good idea since coosa isnt cheap. Right now I am planning the stringer layout in CAD- its probably the most fun Ive had with the tool yet. The biggest obstacle, if you want to call it that, is the addition of the engine cradle. The early BFN stringer shape doesnt lend itself very well to installing one- there is a ~1" jog in the stringer between the front and rear mounts. The rear OMC mount installs directly on the main stringer, while the front mounts sit on 2” tall blocks and shims. Even with secure lags, these blocks flexed a bit with the torque of the BBC, so they have to go.



Since the stringer shape will need to be different (flat) regardless, Ive decided that the best option is to install a newer style engine cradle. Starting in 1990 with the Ski Nautique, newer CC cradles require wider primary stringers, by about 6” (inside to inside of 26” vs. 20”). Instead of the mounts sitting directly on the cradle and having the stringer notched below it to give space for the nuts to attach, the mounts sit inward on angle aluminum tabs that are welded to the cradle. Heres a visual from my ’90 SN:



Since installing a newer cradle will require cutting off and rewelding the tabs to accommodate the 454 anyways, this gives us a lot of flexibility on final stringer height. No need to be super precise with our layup since we control exactly where the mounts will be (both height and distance from transom) by where we locate our tabs on the cradle.

Anyways, here is a quick look at the proposed vs. old structure:



Its not finalized by any means, but its getting close. Here is what the structure will look like with the vents/tubes (teal), cradle/battery box (blue) and the floor (pink):



The plan right now is to foam in the front 3 cavities (up to the 3rd bulkhead).

This is a (very) rough picture of what the cross section will look like (at the rearmost bulkhead). Old structure is in green, new in red.



Like I said, nothing is set in stone yet- still plenty of time to make changes or incorporate new ideas. Comments/questions/concerns are welcome! Ill get some updated pictures this weekend.

I'll be watching this thread. Looks like there is a lot for me to learn from you.

81nautique wrote: I think you should re-title the thread to "Not Just Another BFN Rebuild"

Ha, I dont know Alan- have you seen Gregs, BJ's and Kirk's work? Those are tough acts to follow!

TRBenj wrote: 81nautique wrote: I think you should re-title the thread to "Not Just Another BFN Rebuild" Ha, I dont know Alan- have you seen Gregs, BJ's and Kirk's work? Those are tough acts to follow!

The bar is set pretty high indeed but that's whats so great about this site. You can see the quality of the rebuilds from year to year keep improving. We're turning out some very well done projects these days, not to put too much pressure on you.

Very true Alan, lots of quality work going on around here these days. Hope we can keep that trend going!

Just for fun, heres the what the overhead view looks like with the top deck and accessories installed. I wasnt going to go this far, but knowing where the scoops, seats, dash and everything else are really helps lay out the structural pieces underneath. Of course, I probably got a little carried away with some of the details. Oh well.



Bruce, I dont know about April, though that would be nice. May-June would be acceptable.

Now that the ball is rolling, does anyone have any ideas on how to improve storage in the boat? While its a full 19', it really has no more storage than my 16' Skiers or Tique did- which is to say, next to none.

Right now Im thinking of adding another pod on the passenger side like Kirk (the Grinch) did.



Probably incorporate cupholders like he did, too. I have a black glove box out of a '68 Freeport- what did the 70's glove boxes look like, and where were they installed? Up under the dash? I dont plan on cutting any holes. What about the forward-folding observers seats in the 80-84 Ski Nautiques with non-delux interiors... does that make access under the bow that much easier, or are they useless? Under floor storage somewhere?

BJ mentioned that he'll be moving his battery to the rear of his BFN. I considered that, but I think Ill need as much weight forward as I can get- with the extra 400 lbs of waterlogged foam in the bow, the boat still ran plenty bow high. It would really rise up when coming out of the hole with a few people in the back seat too- I dont want to make that worse with a rearward weight bias. For whatever reason, this BFN doesnt seem to run faster with extra weight in back like the smaller, flatter boats- so no worries there.

What about future growth- anything I should consider adding now with the floor out? I have no plans for a heater, stereo, shower, etc- but who knows what the future holds. Again, I will not be cutting any holes in the dash or gunnels- in case that wasnt clear.

tullfooter wrote: Tim Quit being so vague.    Have you gotten your cradle situation figured out?

Ha, sorry Steve... too much detail?

I think maybe its figured out- I havent spoken with him yet, but Eric is supposedly bringing them back to OH. Once I can confirm that, Ill let you know. Thanks again for your offer!

I have two things to say
1) Atta baby!
2) Wooo hoo !

bj

Projects like this clearly mark this forum as the premier website for ski boats.

Tim - Your upfront planning will make a big difference in the end result, keep it up!

TRBenj wrote: In other words, the stepped stringers open up enough to give it room and I dont think I could bring the main stringers full floor height.

When I looked at the picture at the start of this thread I thought the main stringer was at floor height. But now after looking more carefully I can visualise the step down. That is the same as in Greg's later model BFN. Just the angle that the picture was taken from made it look like floor height.

Yes no secondaries just like the guy who did Kapla's stringer job and that is a much beamer boat than the early BFN. I feel if you are not going to re foam there would be no need for the secondaries. I don't think they add much to the hull strength but would like to hear what the engineers think of that.

lewy2001 wrote: When I looked at the picture at the start of this thread I thought the main stringer was at floor height. But now after looking more carefully I can visualise the step down. That is the same as in Greg's later model BFN. Just the angle that the picture was taken from made it look like floor height. Yes no secondaries just like the guy who did Kapla's stringer job and that is a much beamer boat than the early BFN. I feel if you are not going to re foam there would be no need for the secondaries. I don't think they add much to the hull strength but would like to hear what the engineers think of that.

Thats correct- the structure isnt exactly the same as the later BFN's, but its close. The addition of the cradle drove a few changes at the factory, as did moving the cockpit forward in '87. I agree that the secondaries dont add a lot of strength- ours were no more than 3/8" from the factory, maybe 1/4" (tough to tell since they were so rotten). They will essentially be framing the bilge in our construction. The engine just sits too low in the V-hull to bring the primaries full floor height, unfortunately.

John, have you seen the '82 BFN project on ebay? Youve been playing that "not handy" card too long- I say you grab it and dig right in. You could borrow most of the ideas from my build for yours!

Glad you started this Tim; and looking good!

skfitz wrote: Very impressive. What material do you intend to use for the stringers? Coosa sheet cut and laminated to proper dimension?

Correct- the entire build will consist of coosa. The primaries will be 3 laminated layers of 1/2" bluewater 26. The rest of the ribs and bulkheads will primarily be 1/2", doubled at the floor joints as applicable. The front section of the floor where the front seats mount will be 3/4" with glass on both sides. The rest will likely be 1/2". The front sections that are being foamed will be simply glassed over, save for the raised kickpanel portion, which will be framed with 1/2" coosa to allow for the mounting of panels and accessories.

skfitz wrote: Could you 'splain for the noob? And by noob, I mean me.

I will be doubling up the ribs/bulkheads (so they are 1" thick instead of 1/2") at all the joints in the floor. Clearer?