[dlpanadero]

Bought a 2001 Dolphin Renegade project hull a few weeks ago, under the impression it just needed some cosmetic work (deck/cockpit gelcoat, etc). To make a rather long story short, I found out the next day after doing some sanding that it needed a lot more than cosmetics (I have a separate thread on here where I go into details about that, if you care to search it).

I found out the stringers were compromised and the hull had actually developed hairline stress cracks all the way through directly underneath the stringer/hull bond, meaning it needed full rebuild. Not good. After some choice words I settled on the fact that I had four options:

A) Re-sell the hull and pretend I did not know about the extent of the damage
B) Re-sell the hull and disclose the damage (and flush a fair amount of money down the toilet)
C) Use the boat as is, despite the fact the cracked hull would be on my mind every time I used it
D) Pull up my shirtsleeves and rebuild the f*cking thing

Options A and C were obviously never gonna happen, so after a few days trying to decide whether to keep it or sell it and take a loss, I decided on the former. This thread will simply be photos and description of the rebuild process. Maybe it will be of use to someone down the road who decides to tackle a similar project.

I have rebuilt a Pathfinder tunnel hull and a Mitzi 16 in the past, so here are the links to those if you care to read them:

https://www.microskiff.com/threads/photo-documentary-pathfinder-15t-stringer-rebuild.43144/

 

[dlpanadero]

I could not really find any similar full rebuild threads for this particular skiff, so this project will (and has already been) kind of a learn-as-you-go process. You will see in some of the pics I destroyed a decent section of the deck trying to figure out how the thing was put together. For better visualization, here is a sketch of how this particular boat is built:

I am not a naval engineer nor am I any sort of engineer for that matter. However, in my very humble opinion the structural design of this boat is questionable. On the outboard sides of a robust central stringer, you have two thin, flimsy port and starboard "stringers" that are nothing more than a couple layers of fiberglass laminate. They must have come out of a mold because they are hollow and tied in to the side and bottom of the hull.

In my opinion, the questionable aspect of the design is the fact that the laminate on the inboard sides of the stringers is a good 2x thicker than the outboard - maybe more. Basically you have these little hollow fiberglass structures with radically unequal tensile strengths on either side of them. On the inboard sides of the stringers, it appears the manufacturers used a chop gun to blow about an 1/8" or 1/4" of chopped glass over top of the stringer tabbing. One would of course have to crunch some numbers to determine the exact number, but I would guess the inboard laminate is easily 200%+ stronger than the outboard side.

In doing this, it seems a natural stress point was created. Now I don't know if all of these boats are prone to failure in these same areas, or if this particular skiff experienced some sort of a trailer accident or something that led to the hull and stringer damage. But given the reputation of Dolphin it is surprising (to me). It should not be difficult to build a 16' fiberglass skiff that doesn't fail after a decade and a half.

Longitudinal rigidity comes from a boat's stringer grid. On boats of this size, this should not be a complex engineering process. A stringer should run in a straight line fore to aft, as far as it can go. The taller it is, the more rigid. From what I understand, if the laminate of the hull is consistent throughout, all stringers should be of the same structural integrity. I couldn't tell you what the design purpose of this particular stringer grid was. But then again, what do I know...

 

[dlpanadero]

I am going to rebuild one stringer at a time. This serves two purposes. It will allow me to keep half the deck in (which will make things easier while I'm in the boat moving around and working), and it will also hopefully reduce the chance of the hull distorting in the absence of both port and starboard stringers.

I have removed the starboard stringer and will be starting with that. I will be using PRISMA 4030 preform beams to rebuild. I drove over to the Compsys manufacturing plant in Merritt Island to pick them up. Many boats nowadays are made with these preforms, including (I believe but correct me if I'm wrong) all Mavericks, Pathfinders, and current Dolphins.

In other words the rebuild will be a different design than the original build. I know it is typically frowned upon to adjust original hull design, but... this hull failed. So I believe there is justification in doing so.

The new stringers will be tied into the transom and will run up to the front hatch. The hairline stress cracks stop directly aft of the foreward hatch, so hopefully this will be sufficient. I have left 1 1/2" of the original deck as a ledge - the new deck will be glued to this. It is more typical to have the old and new decks run flush with one another and tie in with a flange bolted on the underside of the old deck, but given the angle of the hull where the deck is tied in it makes more sense to do it this way.

It is hard to see in the pictures but there is about a 1/2 "gutter" created from the thick buildup of chopped glass on the inboard side of the original stringer. This has given me many headaches trying to think about the best way to rebuild this. In a perfect world, the "gutter" would be reinforced and built up with fiberglass to match the thickness of the rest of the hull. Again, a foolish design in my opinion.

Obviously you want your stringer tabs tied in to as much of the hull as possible, so I will simply be laying them down over the "gutter", and then creating more thickness on top with additional layers (strips) of 1708. I thought about building up the thickness of the "gutter" first with strips of 1708, but then you are reducing the bond area of the stringer tabs to the hull.

 

[Plantation]

Good luck. This is a going to be a sweet skiff when you are done with it.

 

[Boneheaded]

WOW, i was after that boat but opted out! Better you than, I sure it'll turn out great!

 

[dlpanadero]

Let's hope so Got a long ways to go

 

[not2shabby]

It'll be worth the effort. Sorry for the position you're in on the skiff, but I think you'll end up with a much better boat and a helluva lot of pride of ownership when you're done.

 

[Monty]

Looks like the right person got a hold of that boat. Sounds like you are more than competent. I had one of those Dolphin 16s in 1988. Jack Broyle sold me the hull and I finished out the deck and made a center console and took care of all rigging. That boat had 2 large square stringers running the length of the boat -- no wood not rot was the slogan back then. I opted for a plywood transom and saved $300 or so, Seems like I paid $1800. Money was tight. I built the top cap on the gunnels with marine plywood and let someone talk me into fairing it with microballons mixed with resin. They let water in and the top cap just rotted. The hull held up great though and so did the glass on plywood floor. I ran a Mariner 60 which was OK but a 75 or 90 would have been better. Great ride in choppy water.

 

[Fishflatmike]

By mounting the new deck on top of the original deck ledge how will you handle the drain holes? Will you have to raise them?

 

[dlpanadero]

By mounting the new deck on top of the original deck ledge how will you handle the drain holes? Will you have to raise them?

Yeah I will have to seal the current ones off then drill new holes and re-fit about 1/2" higher.

 

[dlpanadero]

A lot of sanding done today, starboard stringer will go in tomorrow after work. In the pictures you can see the hairline stress crack in the laminate that was underneath the original stringer. Truth be told I probably could have repaired this by flipping the boat over and laying two strips of 1708 over the cracks. 1708 is very strong, and I doubt it would have re-cracked. But... those stringers would have been on my mind each time I took the boat out and trailered it. Better just to do it all.

I will groove a small "V" along the length of the crack with a Dremel and inject some epoxy resin in before glassing over. After the stringers are done, I will flip the boat over and do the same from the outside of the hull. I will tape over with two layers of 1708. Probably should use epoxy for the outside, but still undecided on that.

 

[yobata]

Have you considered putting a layer of biax down on the entire hull before the preformed stringers? For piece of mind in case you overlooked any other cracks.

 

[dlpanadero]

Have you considered putting a layer of biax down on the entire hull before the preformed stringers? For piece of mind in case you overlooked any other cracks.

Haven't really considered that.. not a bad idea. But still I think I'd prefer to bond the new stringers directly to the original hull layup rather than new material. I think it'd be fairly easy to notice any other cracks.. and I haven't seen any. Seems like it's just that weak area directly underneath the outboard stringers.

 

[dlpanadero]

So here's a good one for ya. In my first post you can see the hairline cracks that run along the underside of this hull. Apparently Tom Gordon looked at the boat and told the previous owner (i.e. the guy I bought it from) to "hang a motor on it and use it." I don't know about you but I wouldn't feel too comfortable running a skiff WOT in the knowledge that it had blown out stringers and a cracked hull. But hey that's just me. Lesson learned do not trust anyone ever when it comes to doing work for you. Want something done, do it yourself.

Anyway... the guy I had bought the boat from had proceeded to Awlgrip over the cracks (a god-awful job, by the way... pics to come later), then sell it to me and not disclose any information about the cracks - despite multiple times asking about the structural condition of the boat.

Of course at this point that's neither here nor there. Today instead of glassing the starboard stringer in I decided to finish cutting out what's left of the deck. I didn't want to lay the new stringer in then have everything rattling around like a son of a bitch while I finished cutting/grinding etc. I hope this weekend to have the stringer job done. Then I can start thinking about flipping the hull over and having some fun on the other side.

 

[Guest]

So here's a good one for ya. In my first post you can see the hairline cracks that run along the underside of this hull. Apparently Tom Gordon looked at the boat and told the previous owner (i.e. the guy I bought it from) to "hang a motor on it and use it." I don't know about you but I wouldn't feel too comfortable running a skiff WOT in the knowledge that it had blown out stringers and a cracked hull. But hey that's just me. Lesson learned do not trust anyone ever when it comes to doing work for you. Want something done, do it yourself.

Anyway... the guy I had bought the boat from had proceeded to Awlgrip over the cracks (a god-awful job, by the way... pics to come later), then sell it to me and not disclose any information about the cracks - despite multiple times asking about the structural condition of the boat.

Of course at this point that's neither here nor there. Today instead of glassing the starboard stringer in I decided to finish cutting out what's left of the deck. I didn't want to lay the new stringer in then have everything rattling around like a son of a bitch while I finished cutting/grinding etc. I hope this weekend to have the stringer job done. Then I can start thinking about flipping the hull over and having some fun on the other side.

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Ok, I have held out long enough. So you bought a boat you are unhappy with. You knew the “poor condition” of the boat when you went back a second time and dropped the coin for it! You have done nothing but bad mouth the seller “who gave you your money back and was more than happy to lose the sale”. Then you started bad mouthing Tom for telling the seller the hull wasn’t worth fixing and to just run it. Maybe not the best advise, but would have to have been there to properly interpret what Tom was saying. Pics are shit for diagnosing a repair and can only go so far off them to see how bad damage really is or isn’t. Then you basically started bad mouthing every mechanic and glass guy by saying “you should never trust ANYONE to do repairs for you and to just do it yourself if you want it done right! “That saying wasn’t meant in the literal sense!” Well, I am both an outboard tech and glass guy and also Detroit and Cummins diesel and have trained on a few gas turbines “many years ago”. So according to you I cannot be trusted to do a proper repair and I absolutely resent that remark! It has been my experience that the guy that trusts no one and bad mouths everyone is the guy that CANNOT be trusted! Sorry for the thread derail, Good luck with the project and tight lines!

 

[jonterr]

Ok, I have held out long enough. So you bought a boat you are unhappy with. You knew the “poor condition” of the boat when you went back a second time and dropped the coin for it! You have done nothing but bad mouth the seller “who gave you your money back and was more than happy to lose the sale”. Then you started bad mouthing Tom for telling the seller the hull wasn’t worth fixing and to just run it. Maybe not the best advise, but would have to have been there to properly interpret what Tom was saying. Pics are shit for diagnosing a repair and can only go so far off them to see how bad damage really is or isn’t. Then you basically started bad mouthing every mechanic and glass guy by saying “you should never trust ANYONE to do repairs for you and to just do it yourself if you want it done right! “That saying wasn’t meant in the literal sense!” Well, I am both an outboard tech and glass guy and also Detroit and Cummins diesel and have trained on a few gas turbines “many years ago”. So according to you I cannot be trusted to do a proper repair and I absolutely resent that remark! It has been my experience that the guy that trusts no one and bad mouths everyone is the guy that CANNOT be trusted! Sorry for the thread derail, Good luck with the project and tight lines!

Yeah
He ended the last thread to start a new one, then ended up bashing the guy again

 

[Finsleft258]

Fiberglass doesn't stick to HDPE (Starboard). Pick a different stringer material.

 

[jmrodandgun]

Fiberglass doesn't stick to HDPE (Starboard). Pick a different stringer material.

He's using Prisma preforms for stringers. It's a starboard stringer not a StarBoard stringer

 

[flysalt060]

Why cut the floor up when you can separate top cap from Hull?

 

[jmrodandgun]

Because the cap and the floor don't come out in one piece.