alumacraft hull flex

[bilge247]

I have a mv 1648 center seat side console and at the end of last years fishing season I was caught in a large storm with about 3 foot waves. Ever since then the boat started to leak. I never had the time to look at it till now.

There are 8 rivots leaking all on the same rib support. All are on the bottom none are leaking on the sides, nor is it leaking anywhere else on the boat. There is no weight forward on the center seat so Im thinking these rivots all started to leak cause of the wave impacts on the front of the boat and the rivots being flexed over and over. visually the leaking rivots do not sit as flush as the non leaking rivots.

Would the addition(battery,tank,ect,) of weight being moved forward and a 1/8 aluminum decking help reinforce the over all structure of the boat? It should reduce the front flex of the hull or am I missing something. Has anyone noticed any diffrence in the frequency of rivot leaks with decking? Thanks

 

[jigngrub]

Was this boat originally designed as a center console, or is it a home grown modification? It sounds like someone has removed benches from a 16' bench boat and installed a CC. This is a typical failure on a boat that has had a bench or two removed because the owner thought he knew better than the structural engineers that designed the boat.

 

[bilge247]

nope all factory. I bought it new. waves where coming over the bow. It was all we could do just to keep pointed into the waves. Beaching was out of the question cause of the rocky shore. Im actually suprised we made it.

 

[Dino]

nope all factory. I bought it new. waves where coming over the bow. It was all we could do just to keep pointed into the waves. Beaching was out of the question cause of the rocky shore. Im actually suprised we made it.

If you bought it new is it still under warranty?

 

[krawler]

Re-buck or replace the rivets, it's not that hard to do. Don't use sealers, glues, paints or anything like that. Fix it right the first time and never look back.

 

[bassboy1]

The deck will help quite a bit.

As far as fixing it, I do agree with the previous poster, in that you should fix the rivets correctly, as opposed to band-aiding it. That being said rebucking is not an accepted repair method - they need to be removed and replaced.

The key feature of a rivet is that it expands to fill the hole. Otherwise, you have, in essence, a nonremovable bolt. But, the expansion of the rivet happens before the head is peened over, so if you have preinstalled rivets that leak, peening the heads further will not expand the shank, but only tighten the heads (back to the bolt theory). While this sometimes can help a very slight leak, it also cause fracturing in the metal around the rivet, and that is bad news.

Best way to fix them is to sand the heads off with a flap disk, knock the rivets out with a pin punch, and reinstall fresh ones. Ideally one would drill the holes out and use the next larger rivet, but I can't say I won't reuse the same holes if they are undamaged.

The riveted Alumacrafts are thin. The last 1648 I worked on was .063. Couple this with a jon boat shape, which isn't necessarily an inherently structural shape, and you do encounter some flex.

 

[bilge247]

The rivets are leaking slowly,about a drip every 10 seconds. is it worth rebucking first to see if they seal up if not then replace? Once I get the rivets to seal up ,I will be puting a 1/8 aluminum floor directly on top of the bottom ribs. Should I also run aluminum sheet along the sides as well? It should reduce the up/down bow flex as well, right? What size rivets do you guys recommend for the floor, to make as strong as possible? Thanks again for everyons help. Ohh I just noticed I misspelled rivet about a million times :roll:

 

[bassboy1]

The rivets are leaking slowly,about a drip every 10 seconds. is it worth rebucking first to see if they seal up if not then replace? Once I get the rivets to seal up ,I will be puting a 1/8 aluminum floor directly on top of the bottom ribs. Should I also run aluminum sheet along the sides as well? It should reduce the up/down bow flex as well, right? What size rivets do you guys recommend for the floor, to make as strong as possible? Thanks again for everyons help. Ohh I just noticed I misspelled rivet about a million times :roll:

Give them one (and only) one hit. After that, you are causing trouble. That being said, if they are leaking one drip every 10 seconds, they are leaking significantly more than the few I've ever rebucked. I would personally replace them from the word go.

Sides would not hurt either. The biggest help would be a raised deck, which is connected both to the side and the floor ribs.

As far as rivet size, I generally run 3/16 rivets on 6" centers for lower decks.

 

[bilge247]

Should I use stainless rivets on the floor, or are aluminum rivets strong enough?