1988 HydraSports 2500 WA Vector

[TWDaddy]

Hey Chessie - I think I just purchased your boat’s brother from another mother yesterday. From the pictures, they look almost identical. I’m not too far from you either, about halfway around the Beltway in Reisterstown.

A lot of what you’re talking about doing are things I’ve thought about for mine. Probably going to get a season in on the water to see how she does and to see if my priorities change after a season of use.

Previous owner had a similar thought to you on the fuel tank. He just swapped out the fuel tank to 110 gallon tank. He gave me the big 192 gallon original fuel tank with the sale. Surprisingly enough, the old tank is in fantastic shape. I’m actually thinking about doing an epoxy coat on it and putting it back in. Not sure.

My engines are the old 1996 carbureted 200hp Saltwater series II that fired right up so hopefully will be good to get me through a season or two but with 28yo motors, I know a repower will be in my future. Look forward to tracking what you do with your boat and how things go with your outboard assessments.

The one thing I may deal with sooner rather than later is my battery setup. I’m kind of curious how your batteries are set up. For mine, I have two in the starboard transom hatch and one in the port transom hatch. They look like they were just stuffed in there. Just doesn’t seem like it would come like this from the factory. Are your batteries in the same location?

Anyway, best of luck with your restoration. I’ll be sure to share anything that may be of interest as I work on mine and look forward to updates and progress for yours.

Here’s a few pics of mine just for fun.

All the best…Brett

[Chessie]

Brett, yup definitely a twin. Hard to believe there are two this close in Maryland. My batteries are the same except 1 starboard, 2 port.


Still not 100% sure what I am going to fully do, but the I am replacing my single engine setup with a pair of twin used Yamahas 115s. Yamaha's Performance Bulletins on similar boats provide enough performance for me.

While the engine is off, I am looking at the potential of rebuilding the transom while it's semi-convenient. I re-drilled the holes for the twins and while the transom isn't perfect, very flaky shavings, it still seems solid. I suspect that this is due to the original glass thicknesses. 3/4" total glass + 1 1/2" wood. Current transom is 2 3/8" thick with 3/8" glass both inside and out. The inner one piece shell adds another 1/8” glass for the top bolts.

Original Rating 470 HP Max. Twin original Johnson 225s 2 stroles are 450# Each.
Proposed 115 HP Twins are 381# EA.


i want to rebuild to be able to handle the loads of 200 HP 4-Strokes for the future, 575#-600# Ea on the high end. Rebuild will be with epoxy coated 1088 Okoume/glass. Currently have 150 # of trolling motor, battery and anchor sitting on the bow 3’ forward of water line

I am attaching every dimensional drawing I could muster to help with the overall context and representation.

I'd like to start getting some layup design details, direction and guidance.

What is the layup for the internal skin. From my understanding 1708 is .05" per wetted layer, which equals 7 layers of glass inside to match the original 3/8"!!!! Is this right?

If these 7 layers are correct, how does the tabbing to the sides and bottom work?

Tabbing for the stingers and one central knee?

Thanks in Advance.

Chris

[Chessie]

So a few questions if someone can clarify

1. Assuming the 1 5/8” wood core. Use two pieces of 3/4” Okoume bonded directly to the outer skin with epoxy thickened with silica

2. Fill the gaps with epoxy thickened with wood flour maybe a little silica

3. Build fillets and then tab transom to gunwales and bottom. Since inner skin is 3/8” assume 7-8 layers of 1708 largest on bottom and working smaller. DO I HAVE TO TAB WITH 12 oz or can all tabbing be done with the 1708?? This avoids air gaps as mentioned post

4. Once inner skin is complete, rebuild stringers and center knee and tab with 12oz to transom skin? WHAT IS GLASS SCHEDULE? Then build up stringers to original thickness with 1708 over tabbing. Can tabbing between stringers and transom be done with 1708 instead of 12 oz?

5. To account for future potential 6 cylinder 4 strokes on transom at 600#, is it worth enlarging the two inner stringers to the size of the center knee to help with loading??


Trying to get some sense of direction to map a plan.

Chris

[Chessie]

So I’ve been doing alot more reading and based on the info in the link below and the transom rebuild thread, I feel alot of my questions have been answered.

https://community.boatbuildercentral.co ... hp?t=66204

One thing I saw in the thread above is the reference to using 1700 for the layers and bonding to the hull

1700 is considerably thinner, about half, of 1708.

The current inner skin is 3/8” which would be about 8 layers of 1708 and god knows how many of the 1700.

How much wood can I add to the transom thickness to make up for the lighter 1700. Can I add an extra 1/4” of wood and then do 1/8” in glass?

Chris

[Fuzz]

So will you be leaving the outside glass and rebuilding the transom from the inside? If so adding more plywood is much more cost effective than trying to build up a lot more glass. Are you doing this work with epoxy? If so 1700 is much nicer to work with than 1708. 1708 can be a bitch to wet out with epoxy. The mat in 1708 does not help as much as it just adds bulk. A few extra layers of 1700 would be stronger than the same thickness of 1708 and use about the same amount of resin.

[Chessie]

Yes, will be leaving out skin intact and doing it from the inside.

Right now, outer skin is 3/8 glass, Wood is 1 5/8”, and inner skin is 3/8” glass, total 2 3/8”.

Is 1 3/4” 1088 Okoume with 7-8 layers of the 1700 reasonable from a strength perspective? “Tabbing” largest layer to smallest, assuming no tape, just the inner skin.

Not sure I ever will, but want it strong enough to support the weight of 2 6 cyl 4 strokes (225hp) or 2 large 4cyl. (200).

Material will be BBC 1700 and their MarineEpoxy the latter I’ve used before.

Chris

[Fuzz]

For me I would want 2-2 1/2 of wood and then the glass. I have seen a rule of thumb that says one inch per hundred horse power but clearly that becomes crazy when you get over 3-4 hundred horses. That much 1700 should work just fine. But remember none of us are marine engineers so are just going off what we have seen and worked for us. I would also use meranti plywood. It is stiffer and a little more rot resistant from what I have been told. Also it costs less so that is always a good thing. Since the plywood is being covered with epoxy fir marine would work as it is even stiffer but it is darn heavy also.

[Chessie]

Original 1988 2 stroke transom was rated at 470 HP, but not the weight of modern 4 strokes.

Does the same methodology apply to the stringer connections with the 1700?

Fallguy, where you B? Your advice is always well respected as well.

Chris

[Fuzz]

Are we talking about where the stringers attach to the hull?

[fallguy1000]

Original 1988 2 stroke transom was rated at 470 HP, but not the weight of modern 4 strokes.

Does the same methodology apply to the stringer connections with the 1700?

Fallguy, where you B? Your advice is always well respected as well.

Chris

Sorry, I have been away from the forum a bit.