Formula rebuild - shine

Picked up my next project boat today.  Its a 1970 forumla 23.  Classic hull that has been the grandmother of many popular 23'-25' center console hulls, a few of the more famous include whitewater 25, first seavee 25, contender, avanti, and half a dozen others.  

This one will be completely gutted and made into a center console.  I will probably bolt a bracket onto the transom, but I have not ruled out making an integrated euro-style transom and stretching it by 2'.

Rough start.....  

Looking forward to this one Joel!

DAYTRIP wrote:Looking forward to this one Joel!

Im looking forward to it too Im just not looking forward to the demo. The plan is to line up another rebuild for a customer so I can afford to hire out most of the demo and finishing

Go for the integrated transom. I think it would look great and be a great tutorial.

stevenaa wrote:Go for the integrated transom.   I think it would look great and be a great tutorial.  

It would look nice, but Im not sure I will have time on this one. I will already be making a custom cap/deck, so I will be looking for "bolt on/glass on" solutions. I may make the hardtop though. Still plenty of time to plan it out. The plan is to rebuild this boat along side another one (for someone else) and the work wont start until both hulls are ready.

got a few hours into the demo today. Its going to be much more work than I thought. The boat had its deck replaced at some point. When the deck was replaced, they bolted 2x4 to either side of the stringers (with 5200), then they 5200 bonded down the new deck (3/4" plywood), then screwed it down with 3" stainless screws, THEN glassed over everything. SO, its going to take few more hours and a few more sawzal blades than I thought.

Remarkably the stringers are perfect, almost 30 years old and not much of any water intrusion and little to no rot. They are still coming out though.

Happy to find a poly tank in there, it can get cut up/out a lot easier than a metal one

looks itchy! Are you doing gunnels and all? I saw a post of some guy who put two 250s on one of these. I would say a little over powered.

Itchy is right. Had I known the deck was this hard to get off I might have passed on this hull.

My good buddy has same hull (avanti) with a single 300 and it runs great. I might go for twins though if I find a deal - a pair of 200's would be pretty sweet - a real rocket ship. There are plenty of whitewater 25 and older seavee/contenders 25's with twin 225's and 250's, same hull.

All new cap for this one, will probably save just the rim so I can tie it in (like you did on the bertram )

Hows the bretram going?

Lots of power for 23 ft. The Bertram is going slow! I have not had a lot of time to spend on it unfortunately. More work this weekend

got in another couple hours of demo today. These 37 year old stringers are completely dry and solid. A little bit of a shame to cut them, but when you look at the time and money it takes to put together a nice 25' CC it make sense to go ahead and have new stringers.





Starting to think about stringer grid. Had planned on making a pair of fiberglass trapezoid stringers (foam filled), but now Im leaning towards 4 composite sandwich (coosa/penske type), mainly so I can get use of the beam to make fish boxes in the stern between stringers. Would also open option of using saddle fuel tanks.

Makes me tired just looking at it That's a big project for sure. Great hull though and certainly worth it.

Cracker Larry wrote:Makes me tired just looking at it

I can only take 2 hours at a time, max. Demo is pretty brutal.

Picked up a new sawzall blade and hit it for about 1-1/2 hour today. Had to stop when the dumpster was full. Its coming apart much easier now that I am past all the 5200 and stainless steel screws







More demo to come ......

You are the man buddy. Why do you want to do the stringers? Just so it is 100%?

DAYTRIP wrote:You are the man buddy. Why do you want to do the stringers? Just so it is 100%?

yeah, I figure Im going to put a lot of money/time and my hide overtop of those stringers. Its a nice feeling knowing the person who laminated the stringers on your boat

Joel, try a diamond blade in an angle grinder, like the type used for cutting tile. 4" and 4.5" are typical and you'll stop eating up reciprocating blades. If it's a good angle grinder, with a vacuum port on the shroud, you'll be less itchy too. I'll assume you know about baby powder, hair spray and liquid glove . . .

Hey Paul. You have a good point. I do have a grinder with cutoff wheel that Im saving for the more delicate work (removing liner and transom skin). I have not tried the tile blade, just use metal cutting blades, so I think I will give that a try.

I dont mind an itch, I wear pants and long sleeve shirt along with a dust mask, in this heat (outside) its not fun, but I knew that going into it

What is the hair spray and liquid glove tricks? Does the baby powder really help?

getting back to the formula.... have most of the demo work done, still have to grind out the rest of the foam from around the tank, then remove the core from the i/o transom bump-out. Braced the sides of the hull before I cut the last couple feet of the cap off.

For stringers, I have decided to make fiberglass trapezoids. I will still have 4 of them, but the spacing will be different. I am making the forms for these on a mold, then will trim to fit into hull, then covered in glass to get the total thickness. Will use same mold to make transverse framing (grid system). The tops of the grid pieces will be 5" wide, so I have room to run chases inside them. They will be filled with expanding foam after they are glassed into place.







Here is the mold going together. Its MDF with a plastic "cap". The plastic cap is just a short cut to getting the shape I want. The MDF will be epoxy coated.







I have the first inventory of transom core and foam core being shipped next week. Will be stocking the transom core in 3/4" (26 lb fiberglass reinforced foam) and the lighter version in 1/2" (for decks/caps/etc), also getting 25mm thick pre-glassed honeycomb panels. I will be using the honeycomb for the formula sole.

How would the honeycomb work for a hardtop Joel? Finished sole last weekend with the 1/2 " meranti I had left but still have a painful amount of fairing to do.

lawtoolguy wrote:How would the honeycomb work for a hardtop Joel? Finished sole last weekend with the 1/2 " meranti I had left but still have a painful amount of fairing to do.

Yes, its used on many hardtops. If I end up building a hardtop for this boat, it will most likely have a honeycomb core.

Finished sole last weekend with the 1/2 " meranti I had left but still have a painful amount of fairing to do.

Thats a big step. I can only wish I was at the fairing stage on this project

making mold for stringer/frame parts

Capped the uprights with another piece of MDF, then rounded over and epoxy coated. Faired the joints a little before first resin coat. Will get another epoxy coat, then a sand, and then one last epoxy coat before its ready,

Looks good Joel. I did the same thing on the ski boat I did but a much narrower section. Works great. How many layers are you thinking?

The shape of this transom does not make for an easy core application, I was looking at putting in 2 x 3/4" transom foam int he i/o bump, followed by a third layer across the whole (curved) transom. Knowing how much putty, grinding, mess that is going to be I have been thinking of a better way

I am considering going with a poured transom for this boat. I have always disliked the pour transoms,most of the time they are used as a short cut and you can never ensure a good bond. In this case I am able to ensure a bond (all the old outside skin has been ground). Plan would be to tab (glass around outside) a piece of transom board straight across the back, brace it, then pour a ceramic reinforced transom. Then a new inside glass skin would be put in. Finial thickness will be substantial, well over 3" in the center. Besides a little extra wait, and cost this might be the best option for this boat.

I may fill the I/o bump with transom foam before pouring, that would save weight and cost.

I may go with twins on this boat, so the added transom strength would be welcome

transom is just about cleaned up

What about just cutting the bump out off the boat and re-skin it in that area? A piece of melamine on the outside and lay it up. It would make the bracket easier. Other benefit is you could stop grinding now!