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74 Vector 4 stringer rebuild

Restoring your Hydrostream or just giving it a small makeover? What better place than to show off your project. Big or small.
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74vector
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74 Vector 4 stringer rebuild

Post: # 3299Post 74vector »

Hi All,
I had responded to the 76 Vector rebuild thread describing what I had done to my Vector core and it was suggeted I start a new post with pictures so, here it is. Here is a copy of that post plus added some pictures to go along on this post. I am not suggeting that this is the way but maybe help . Sorry but I may not have loaded them in order. Another thing to notice is the side supports for the deck at the rear motorwell and the brace in the middle that the trim pump mounts to. There are similar supports at the seat sides, which also makes for a small cubbie space for storage. Looking at a lot of older Streams you see spider webing due to the deck flex from people sitting on the cockpit side or the motorwell, I thought these supports would stop this from happening where this boat had none. The black coating in the last few pictures is just a thin final coat of blackened epoxy, Carpet will go in when interior is completed widsheild will go on, motor mounted, I have a set of correct vintage Merc gauges and a vintage dual rideguide cable system. Interestingly the early streams came witha real wood grain wheel made by Superior rather than the Merc fake wood grain that came soon after. They used a special adapter to fit it on the rideguide system. I did find an original wheel too.
Here is the old post:

Image I have just completed my 74 Vector recore and went through the same core material selection stress that you are going through. Just for background the boat had the low floor, foam filled seatbox for back to back seats and the not to tall 2 stringers on the pad outer edges.
The boat was pretty much a garage queen but still had extensive core problems, so it all came out, the rotted stuff is easy to remove the non rotted stuff was difficult, I scribe cut it with a circular saw making a 1x1 checkerboard pattern about halfway down into the balsa. I then used a Sawzall with a long blade to cut these squares flush to the bottom of the boat, the blad conformed very well to the bottom and did not punch through in any way. I have lots of pics. I then did the final grind to smooth and remove residual balsa.
For new construction and I have to say upfront, weight was not the primary concern, it was longevity and future stresscrack prevention, I did this boat more with an eye towards originality rather than out and out speed.
So I used Balsa core with 4 stringers,( solid 7/8 mahogany) and Okume Marine Plywood for floor and frames.
Here is my thought process: In taking the boat apart it was pretty obvious why the core got soaked, the area under the floor is shallow, did not drain well, and there was no ventilation. There is a limit as to how careful the factory could be in gap free glass work and polyester resin chop glass is permiable and will wick water if it is left long enough. This underfloor area was always exposed to water and moisture which once allowed the balsa to get wet, water wicked out to areas not under the floor and in my case even the lower corners of the transom.

Material investigation revealed that from a strength impact resistance etc. Balsa is superior it's only downside is potential rot. I figured I could overcome this shortcoming in several ways. First was NOT to extend the balsa under the floor, keeping it high of the bilge area, second, be more careful with workmanship, third use epoxy resin and better glass fabric than chop. To gain back lost strength of the NON balsa area under the floor I used 4 stringers and several glass laminations to thicken the hull in this non balsa area. The two inner stringers went where the original ones went except I made them 4 inches tall, the second set went in the chines that the original edge of the floor sat in, these stringers were about 2 inches high. So overall the new floor would sit about 2 inches higher and was a little wider than original, a compromise on cosmetic originallity but only a VERY decerning Hydrostream eye could tell! I used mahgany for the stringers as they would be far less prone to wicking and rotting than plywood on edge. I used 3/8 marine Okume for the floor which is a very light but strong plywood, much lighter than he fir plywood that was used originally, it is 7 laminaton ply and is much stronger and stiffer than original despite lighter weight.
For glass work, initially, I laminated stitched biaxial cloth with a chop backing chop side up onto the newly cleaned hull, I did one half of the hull at a time, a contiuous sheet from near the bow right up the sides and all the way back to the transom and allowing about 12 inches of overlap in the middle, before this cured I laminated down the balsa to it with thickened resin. I did one side so I could work form the other , once cured I did the remaining side. once this all cured I sanded the stray epoxy hand prints and foot prints from the bare balsa top to prepare for the top layer lamination. This was the same stitched biaxial with chop back cloth used on the bottom but this time the chop down to the balsa, the chop sides faced the balsa because they make a reisn rich layer to promote bonding the the balsa. As before I did one side than the other front to back continuous, with same overlap in the middle. When done this gave me four layers of glass in the balsa free middle bilge area. I then laminated a stripe down this middle giving 5 layers of new laminate. I then glassed in the stringers using Biaxial tape.
It was quite a fiddle doing continuos laminations but I felt it would be worth the effort.
The floor was cut to fit and I put a thin layer of standard 90 degree boat cloth down on each side to stiffen it and to give water/moisture protection. The floor was then bonded into the boat along the stringers and bonded, glassed the edges. The edge of the floor just covered the edge of where the balsa ended, so there is no step on the top sides, but plenty of space for water to drain and air to circulate under. The end of the floor in the tank/battery area has cutouts to provide ventilation into the areas between the stringers. I put a deck plate into the bow under deck raised floor area so when the plate is removed there is free movement of air from bow to stern under the floor. Overkill I'm sure. I weighed everything used and compared it to what weight the stock construction would be eliminating the "extra" stuff and i figure overall the boat weighs about 30 pounds more. The extra stuff was offset a bit through the use of the lighter plywood and less balsa.
The seat boxes and tank trays where alos made using the lighter Okume so these would up lighter than stock.
I did not fill the seat box with foam, rather I made storage space by leaving it empty and having the front seat bottoms remove for access in a simialr fasion as the back seat bottoms do.
The boat is now going out for a clear coat on the deck next while I do some interior work. The tough part on th eboat is done. I still have to dig into the motor a vintage correct 74 inline 1500. I have tons of pictures if helpful.
I'm not saying this is what to do but thought it might be helpful to hear.
Good luck!
Randy
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Re: 74 Vector 4 stringer rebuild

Post: # 3300Post HST4ME »

Boss Moss....awesome!
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Re: 74 Vector 4 stringer rebuild

Post: # 3303Post ccrick »

:agree: looks good, cool color!
1980 Viking
150 Black Max
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Re: 74 Vector 4 stringer rebuild

Post: # 3304Post VultureNo2 »

Great thread Randy :up: My Vulture only has core under the floor. There is no core up the sides like on your boat. I don't know if this technique will work for me. Any thoughts Hippie, since you have similar issues? I wouldn't have any core at all :?: Extra glass and stringers seems like an attractive alternative. I really like the idea of getting air flow up and down the entire boat under the floor. Also your front seat box is interesting. I like the extra strength that you get with the middle of the seats coming up the sides and creating storage areas, but would probably try to come up with something that would not have a similar step in the middle as yours. Going with the lighter wood is a great idea. I have a similar mindset for strength vs speed. My main objective is a great barefoot boat. Thanks for all the advise. :boating:
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Re: 74 Vector 4 stringer rebuild

Post: # 3314Post kytekeith »

Thanks Randy for the pics. You have added food for thought. Extra glass sounds like a great idea to keep any worries of rot under the floor away. The few pounds of extra weight is a small price to pay for piece of mind.

How did you come up with how many layers to use to duplicate the streangh of balsa?


I also would like to find an ole tower to put back on mine A post 79 150 with the coil per cylinder would be awsome . The looks of that tower hanging off the stearn is mean and keeps the original look.

Keep the pics coming.
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Re: 74 Vector 4 stringer rebuild

Post: # 3317Post 74vector »

In response to the previous posts:
Keep in mind that the box like structure for the seats really adds two frames across the width of the boat. I believe that's part of the reason why this was done this way originally. I think the Vulture had this seatbox in it for back to backs also and then a bench in the rear. The boat winds up with a frame at the bow because of the way that raised area has a footrest which doubles as a frame then two frames at the seat box and finally the tank area has a fourth low frame all this aids in preventing the hulll from twisting when hitting off angle waves. The plywood floor and stringers also prevent twisting as well as adding length wise rigidity. If you think about it it is similar to an I beam with the stringes being the web and the floor and hull being the flanges. If you notice there is not much space between each stringer centerline maybe 6 or 8 inches max. so there is not much unsupported hull anymore so I felt that 5 layers of
BI-DIRECTIONAL (important) would be more than enough support over these short distances. The riding surface is pretty beefy I can tell you it's like jumping on a concrete sidewalk. I am fortunate to have been in the boating industry and know a builder in CA, (Sanger Boats) and got an opinion from a 50 plus years in business builder as to strength.
I did comment on the long line Barefoot performance of the in the 76 Vector restore post if you did not see it. If you are going to use a boom you had better put some deck support similar to what I did or you will most certainly crack the deck.
As far as inlines go the later 115 Prop shaft H.P. with seperate coil motors used low dome pistons and were down about 10 h.p less. they were really about 140 h.p. at the crank. I have found these to be a little slower and not quite as punchy but they are great running motors. I have not seen any difference in a "J" XS block than a stock 1500 block as a point of interest. The low domes have the deflector machined down shorter which lowers the effective compression. An inline Merc sure looks fantastic now matter which one it is!

Randy
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Re: 74 Vector 4 stringer rebuild

Post: # 3320Post Hippie459MN »

Boat look great and I love the color. I always was a sucker for green. :D
-Kevin
Project Vulture | Project Vector | Project Vamp | Project Vixen
The Vulture Wish List | Project CobraJet

1977 HydroStream Vulture - Worlds longest ongoing project. :eek:
1982 Hydrostream Vector
1982 Hydrostream Vamp
1973 Hydrostream Vixen
1976 CobraJet Jet Boat - Outboard conversion project
1976 Pontoon - aka The Family Truckster
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Re: 74 Vector 4 stringer rebuild

Post: # 3774Post kytekeith »

Thanks again Randy for all your input you have provided . I have just finished rereading all your posts on my thread and yours. I too am not worried about adding a few extra pounds just looking for peace of mind knowing i don't have to worry about rot. When completed my stream will be pulled around the south east u.s. as my off time toy. It will be exposed to the weather alot while being towed because my experience with covers is they don't hold up well to interstate speeds. Maybe someone has ideas on good covers that hold up .

I am going to follow your ideas on no core below the floor at least on the pad between the stringers. I also am thinking about four stringers for added suport. I wanted to place the floor back on the strake like original and the place i am looking at for the extra set of stringers is on the first strake outside the pad. This would put the stringers only inches apart.
I am going to use coosa for the stringers and the placement locations will make the second set taller. Do you have any thoughts on this selection?
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