boat build, 197* tri hull bass boat to cc conversion

[jbcurt00]

Expensive and heavy compared to plywood amd not strong enough for use on a transom.

The problem, IMO, isnt the wood or flotation foam used in a boat, nor is water the enemy. Poor quality control or lack of attention to detail during construction arent the problem either.

Basically, IMO, the vast majority of problems associated w rotten decks, stringers and transoms could have been avoided if previous owners did better maintenance and stored the boat properly.

All that ^^^ is why I recommend using the best plywood you can reasonably get, be diligent w surface prep and the glass work, use adequate flotation, then keep the boat stored properly when not in use : Bow up, well covered w the drain plug out.

The Lowes link you provided is $37 per 8ft 1X8 pvc plank. You'd need 6 to replace 1 4X8 sheet of plywood. I could get 2 sheets of highend 4X8 3/4in marine plywood for that.

 

[solareclpse2000]

i totally and strongly agree that the biggest difference is made with proper maintenance, however, i like to remove wood any chance i get, because eventually, even if 30 years down the road, it will rot. especially in a salt water area like here on the coast. and i believe in maintenance, but i cant trust my young son to do so with his first boat. but, weight i am certainly concerned with. i did feel heavier to me than just wood when i picked it up. maybe i wall use it only for the stringers and not the deck. i was trying to find it in 4x8 ft sheets. it may exist, and i can probably find it if i search for it. but as of this second it was us an impulse thought i had the other day. if it would cost the same or even just a little more than marine grade plyboard then maybe ill lean that way, if i can figure some more out about it. what i may do is buy a couple 1x4s of it, and wood, and compare then with bend tests, break tests, ect. if i get around to that i will share the test and results on here for everyone. what kind of tests would yall like to see to compare these items? im thinking a bend test, both vertical and lateral...... comparing the weight of the boards......and the ability of getting the epoxy to stick. its worth checking out, and a consideration as possible if it can pass these tests to wood. i was thinking about some sort of flex test? not sure how i could do that though........ what other tests yall think i should do?

 

[sphelps]

The most important test for me would be adhesion .....

 

[jbcurt00]

If I ever considered using seacast or that pvc board for stringers, I'd probably not use either because of cost and added weight.

If I really didnt want to use wood stringers or deck I'd probably use rigid foam and form a wood free stringer over it and decide how many layers of glass (and what type of glass) I'd nees to use to mimic the missing wood cores. Same for the deck.

Truthfully I dont know how I'd go about estimating the extra glass needed, But someone else here might be able to do it.....

 

[sphelps]

Weight is not an issue with seacast ... It' actually slightly lighter than wood .. But cost ..

 

[solareclpse2000]

Ok, so i got a little progress done, well, demolition anyways. The stringers, transom, and deck were all far worse than i expected. Ill post up some pics next, soon as i upload them on photobucket.

As for the pvc, i got some small testing done and determined the following

On 1x4 control pieces, the pvc is was about 2oz heavier.....per foot!

Under the same weight (20lbs) the pvc bends an additional 6 inches, with the flat (wide side) and about 1 inch on the tall (thin side). All numbers rounded up to the nearest inch.

On the tall side, (6ft long) the wood fractured at 285lbs, with a lil push to finish it off. Quite impressive actually. The pvc under just 215lb bend to a point which it would not return back to its normal line, and left permanent "buckling" i would suspect this to be worse, on a hot summer day

And finally, adhesion, epoxy just simply will not bond to it. The only way i got decent adhesion was to spray the pvc with a standard spray etching primer, but i would be concerned over time this primer could wear and create a tiny gap, which would allow the pvc board to start "floating" inside of the glass outter layer.

So, pvc is definitely out of the question, and sea cast is just out of my price range, so i guess marine grade wood it is.

Now that, that is out of the way, moving on.
So in the pics, it is clear these stringers are very small at spots, about an inch tall near the middle where they end, and only about 1.5 wide. 1 question i had is can i do taller stringers, and raise the deck a little, maybe even just an inch or 2 if necessary.

Whats the best way to cut out the transom glass tabs, with out penatrating the outter hull? Or should i just keep sanding till it looks right?

I was also thinking of adding 2 more stringers, 1 out board of the current stringers, near the hull sides. I will be adding bulk heads and such for strength, and foaming in the hull below the deck with a quality closed cell flotation foam, 2 part liquid, etc.

Keeping in mind this was a bass boat which im turning into a center console skiff, i will likely leave the portion of the deck, under the console reccessed so to add some space for the fuel tank, and batts.

I think i have propulsion figured out. For this boats length, beam, transom in the calculator, the max hp is 60hp, so i will likley go with a mercury sea pro 40hp. Since it is going to be built for my son, n i dont need to temp him with full powered turns on a 60hp. The outboard im going to mount on a jack plate, on a armstrong bracket, 18-24 in extension.

The outboard, and fuel tank will be setup on quick disconnect fittings and easily removable, so that he can pull the fuel n motor, and mount an electic trolling set up, for the local electric only lakes. Im thinking of building a bracket to house the minn Kota dual motor mount trolling motors, 160lb thrust, and maintain steering at the helm. Just the thoughts on a good "do anything" set up.

So is the plan, and i guess any great creation begins with destruction. So tomorow i will continue disassembly.


Also, if anyone has pics or links to a good write up they have done, or pics of stringe, transome, deck jobs they can share i would appreciate it. I love looking for new ideas, and finding solutions that others have used, to cut back on learning by error. Lol. Thanks again everyone.

 

[sphelps]

I see no reason why you couldn't raise the stringer height a little if you want ... I wouldn't raise drastically but a couple inches would be fine ... JMHO.

 

[solareclpse2000]

Ok, i didnt think it would be an issue. If i raise the stringers, it will raise the deck too. I only have about 15 inches above the deck, up the gunnels. But i can sacrafice some of that. I saw someone had sent me a PM. But my phone and computer are both acting stupid, so the message has just disappeared. I also cant get my photobucket to work right. But ill try and get my computer fixed and get the pics up tonight.

Also, i have these 40 grit flapwheels for my grinder, and have found they are WAY to powerful for taking off the gelcoat. They eat right into the glass. Whats a good grit, and method yall have used to remove the gelcoat from the outter hull to strip and re gel coat without eating the glass?

 

[ondarvr]

You don't use a grinder to remove gel coat unless you need it removed so you can glass over that area.

Polyester resin will bond well to many types of PVC boards, the issue is you aren't adding any strength with the PVC, a hollow stringer would do about he same thing at a much lower cost. If you aren't counting on the on the PVC to add strength you just increase the laminate a bit, so you could use wood and do the same thing and it rotting away wouldn't be an issue, but with more glass around it the likely hood of it rotting is reduced.

Adding stingers isn't of much value, but there isn't much of a downside either, other than weight, time and cost.

 

[jbcurt00]

Why do you want to raise the stringer height?

 

[solareclpse2000]

At first i wanted to add strength, so the thought was to raise the stringers, and for some reason i think, shorter stringer means less strength, tho, that is probably wrong. I want to reccess the deck, under the console a few inches to have the space to put the fuel tank, and still have space above the tank for batteries, all while keeping the ability of using a tank i can remove easily, when setting up for a day on the electric only lakes, but to have enough reccess below the deck, would mean i have to build the stringers, and deck, higher. If that all made sense. Its alot of systems to mount in small space. Gas tank, hoping for a 12 gallon or 18. And 4 batts. 2 for 24v bow mount trolling motor, and 2 for main systems ( A batt, B batt setup) trying to manage systems, weight and space has been the biggest pain in the plan

 

[ondarvr]

Yes, making the stringers taller will make stronger. But did they fail in some way over the last 30 years of use that leads you to believe they need to be stronger?

I think you said you wanted a removable 12-18 gallon tank, have you ever tried to move a tank that size that has much fuel in it? And you aren't supposed to put portable tanks in enclosed spaces.

 

[solareclpse2000]

It doesnt appear the stringers have failed as in broken.... rotted inside out due to poor glass encapsulating, seperating away from the hull, i think also due to poor glass work, is what i have. The forward stringer along the keel has split, but i camt tell if it was from stringer failure, or if it was glassed as 2 sectiins that seperated. Yet, i want to build stronger because if im gona build from scratch i want redundancy, and have the chance to improve for my use. This started as a bass boat, and looks like it did a whole lot of sitting around in the weather, more than actual use. I will be using it as a center console, alot in the saltwater intercoastal water way bluffs.

A 12-18 gal tank of water wld weigh about 5 lbs of plastic tank, and 96-144 lbs of water. Assuming it was full to the top. That is easily a 2 person lift. And, gas is slightly lighter than water. I will likely stick with 12 gallons, simply to keep over all weight down. 12 gal with a 40hp outboard should give me more than sufficient range for what im trying to do. 12 gallons, assumung it was filled to the top, i can pull myself...... not that its fun, but possible and acceptable. If i could get a 6.6 or 8 gallon tank to cover a 20-25 mile WOT range i would probably stick with that. But im still working on figuring actual fuel consumption,,,, without having the ability to actually run it n test it. So, i figure, build and start with the 12, and if a 6 will work, then switch it later. Always easier to build a bigger compartment and go with a smaller tank, than the other way around

And as for the enclosed space, i plan on using that same vent hose and air scupper setup that you would use for a sealed compartment tank. I could mount a fume blower fan, like an inboard has, but i dont think it would be necessary. I could also leave the back of the console open where the tank is like most small skiffs too, but i prefer not to.

 

[solareclpse2000]

So weird, my message box says 1 new message, but when i click on it,my message center inbox is empty?

 

[ondarvr]

Typically people go with two 6 gallon tanks, it's just far easier to work with.

There are tanks designed for enclosed spaces, they are vented to the outside of the hull, portable tanks are not approved for enclosed spaces like you described.

If you want to raise the stringers (floor) so it can be self bailing, that can be a good thing for a CC, if you just plan to make it stronger, with no indication that it needs it, then it can be a wasted effort and reduce rail height for no reason.

I understand what you're trying to accomplish, people here will just try to guide you through the project with the least amount of wasted effort and money.

 

[solareclpse2000]

I agree, and if i can make decent range on a 6 gal, that will be my first choice, does anyone here have a realistic range for a 6 gal tank, 15ft skiff, 40hp motor?

Im going to have to figure out a solution to the fuel tank, so that its not enclosed, but still easily removable.

I would like to raise the floor. But just 2 or 3 inches should be sufficient. The stringers are totally shot, and since they need to be redone anyways, i might as well strengthen them while im at it.

Whats a good rating for marine grade wood? At my local lowes when i mention the words marine grqde wood, they look at me like im crazy, so if i can tell them i need wood with "X" rating, maybe that will help.