oil canning!!

[Karyon]

I've noticed underneath the rear of the boat the bottom is starting to oil can? (I think that is the right word for it) When the boat is in the water and the water ballast is full , does the dent come back out?

What causes this?

The boat does have many trailering miles on her, from AZ, to Mexico, to BC Canada , to Alberta, to Montana , and now back to Alberta. and some shorter trips in between.

In the last picture you can see the white line and that almost looks like a crease.

 

[Crazy Dave Condon]

I am probably the one who should answer. Yes it will come out in the water but not all the way. The big question is what caused that. Please respond to these questions. Do you have a lot of gear stored in the rear port side which I doubt is the case? Is the bunk board laying completely flat against the hull down the entire length on the port side of the trailer? Are all the supports with attachement brackets secure on the port trailer bunk with special interest to the middle support? Can you tell me if the bunk board has cracked or broken which may entail removing the carpet on the port bunk board.

What is happening it appears that the bunk board is forcing the hull upwards on the rear due to the board coming up as I saw many times when a board broke, supports/brackets failed and so forth. Now you need to go back and check and please a better picture of the entire bunk so I can look. I may suspect that a bolt on one of the supports may have come off or broken with age.

 

[Karyon]

Dave,
I don't store much stuff in the stern of the boat, with to much weight the boat will sway behind the vehicle.

I do travel with the motor and rudder on the stern.

I have taken (hopefully) better pictures of the bunks. I am pretty sure that these are still the original bunk boards and kind of poking into the wood with a screw driver the wood is pretty soft and rotted I would suspect.

Obviously I need to take the boat of the trailer and replace them

 

[Crazy Dave Condon]

I appreciate the photos which also tells me one other thing to replacing the bunk boards. The height of the middle stalk or support is not long enough and on occasion remember replacing them as there is no length left which to raise and redrill. You can buy that stalk or order it from a trailer supply. Maybe Northern Tool or Farm Tractor might have them. I can see a small clearance in the middle of the bunks where the support is. That should take care of the issue replacing the bunk boards and raising that stalk to support the middle section of the hull. Thanks for the photos

 

[Doug J]

I think my boat has the same issue, a slight indentation. I'll be replacing my bunks too.

Crazy Dave,
Have you ever seen where this causes damage to the water ballast tank? Or does the tank provide extra strength?

 

[Crazy Dave Condon]

Generally it never affected the ballast tank lid. I think you will be ok

 

[CloudDiver]

Dave,
I don't store much stuff in the stern of the boat, with to much weight the boat will sway behind the vehicle.

Your sway isn't being caused by too much weight in the boat in general, its too much weight aft of the trailer axle causing a reduction in tongue weight. Try storing your gear as far forward in the boat as possible. That should reduce weight behind the axle in increase tongue weight. If the sway does not stop after that, moving your axle (or axles) back is the next step. Just two or three inches can make a huge difference in stability over 55mph.

 

[Crazy Dave Condon]

CloudDiver is correct about the swaying when too much weight is in the back. For safety, 10% of the towing weight should be on the hitch; otherwise without brakes, swaying of any trailer can cause loss of control and the only way to correct that is momentarily increase speed to pull the sway out. THIS had nothing to do with the oil canning. I think the two causes is the bunk board needs to be replaced and the center support needs to be raised but in your case the support will require a new section.

 

[GGordonWoody]

Yaaar - that's the damn finest hull I've ever seen! As another of Sir Dave's H23.5 disciples, that dent and crease makes me a bit uneasy...

I do travel with the motor and rudder on the stern.

Just a suggestion, apologies if this has been mentioned. If you have a truck, I would put those in the bed, along with a dolly, and haul my jammies below deck. These boats have 20+ years of trailering, and the hulls seem quite thin (as compared to a power boat or even a 26M). And if that load on your tail is causing sway problems, all the more, you need to get that off so you can swerve hard to knock down deer and bears, and avoid beer cans and damn potholes! One more thing. I might minimize boarding her on the trailer. Keep yer grog on the front seat where it belongs.

Sir Dave -
1. If the situation doesn't clear up, would you recommend reinforcing with an application of Kevlar and epoxy down the inside?
2. As for the trailer, would you recommend wider bunk lumber, say 2x8 or 2x10 (properly supported of course)?

 

[Crazy Dave Condon]

Good morning sir.
As for the interior of the hull, leave all well alone but ensure that the seal of the fiberglass lid to the waterballast tank in that area is not leaking. You will not get all of the bulge out but most will come out eventually which is why dyvancell was used in the mfg. of the hulls and decks.
As for the bunk boards, no more that a 6 inch width.

 

[Doug J]

Crazy Dave,
Did you mean Divinycell? I tried to google it to learn more. It says it's foam core. Is that correct?
These boats aren't foam core, are they?

 

[Crazy Dave Condon]

take some resin with hardner and put it on any foam and see what happens. It is layered between the wet fiberglass and shrinks.