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24-05-2019, 10:37
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#1
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Registered User
Join Date: Jan 2015
Location: Seattle, WA
Boat: 1980 Pacific International Marine 41.5
Posts: 710
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New Beneteau's - How is the decks secured to the hull?
So my dock neighbor just got a brand new Bene Oceanis 38 - Delivered in Feb 2019.
What I find incredibly interesting about the new boat beyond the hard chines is how they've secured the deck to the hull.
They have teak toe rails, but it appears that the deck joint has a white polysulfide(i assume) caulk line. This caulk line runs from bow to stern, down the stern sides and down towards the water(below) the drop down swim platform.
Is this common of NEW builders to use a caulking joint on the external side - exposed to the elements for creating a watertight seal?
What is holding the deck/hull together? I am assuming they have some sort of bolts bedded in the laminate but I was also thinking maybe they used something like 5200?
Would make me feel quite nervous having that caulking joint being so exposed and also not having any bolts through the joint.
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24-05-2019, 11:08
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#2
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Registered User
Join Date: Oct 2012
Location: Med.
Boat: Amel 50
Posts: 1,016
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Re: New Beneteau's - How is the decks secured to the hull?
It is my understanding that there are screws, or bolts (I am not sure), through the toe rails joining the deck with the hull.
On my ex-Lagoon 450, there were using screws by the side stays. Due to the hull flexing and mast pumping, the screws sheared and I got leaks. I replaced the screws in the area with larger bolts, SS backing plates (inside and out) and layers of fiberglass cloth on the inside. Not a fun job but needed to be done. This may not be the case for monohulls as they do not flex as much.
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24-05-2019, 11:20
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#3
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Registered User
Join Date: Oct 2015
Posts: 2,007
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Re: New Beneteau's - How is the decks secured to the hull?
SCREWS???? WTF? You mean self tapping screws? That’s so bad it’s almost criminal. That’s not how you build an oceangoing boat!
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24-05-2019, 11:34
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#4
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Senior Cruiser
Join Date: Mar 2003
Location: Thunder Bay, Ontario - 48-29N x 89-20W
Boat: (Cruiser Living On Dirt)
Posts: 49,082
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Re: New Beneteau's - How is the decks secured to the hull?
“Our hull to deck joint with wide return flange is one of the strongest in the industry. It is chemically bonded (polyurethane mastic) with mechanical shear fasteners (screws and nuts/bolts) - 100%reliability with no recorded failure in millions of miles of tough ocean conditions.”
➥ https://www.murrayyachtsales.com/wp-...etter-Boat.pdf
However:
"Hull-deck joint screwed, bonded and trimmed with 1 toerail”
➥ https://www.beneteau.com/sites/defau...S_light_en.pdf
__________________
Gord May
"If you didn't have the time or money to do it right in the first place, when will you get the time/$ to fix it?"
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24-05-2019, 12:21
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#5
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Registered User
Join Date: Oct 2012
Location: Med.
Boat: Amel 50
Posts: 1,016
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Re: New Beneteau's - How is the decks secured to the hull?
Quote:
Originally Posted by billknny
SCREWS???? WTF? You mean self tapping screws? That’s so bad it’s almost criminal. That’s not how you build an oceangoing boat!
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Well, I agree with you regarding screws. Like I said, the area I fixed had screws on our 2012 L450. I don't know about the rest of the areas, as most are not that visible without removing cabinetry backs.
For whatever it's worth, we spent 3 seasons in the S. Pacific and saw some major, to us, storms and waves. Our L450 took care of us. We never felt unsafe.
You get what you pay...
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24-05-2019, 13:32
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#6
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Registered User
Join Date: Jan 2015
Location: Seattle, WA
Boat: 1980 Pacific International Marine 41.5
Posts: 710
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Re: New Beneteau's - How is the decks secured to the hull?
Thanks for posting those links Gord!
When I get home tonight I'll have to take a look at the toe rails. One thing I noticed is that the rails are not running the full length of the hull, rather there are quite a bit of space between some sections.
@boom - On your old Lagoon, did you have a polysulfide compound that was exposed on the exterior?
One thing I noticed in the first link posted by Gord was that it's from 2014 and I believe the model is different than the new models.
I'll post a photo of the boat tonight, but I definitely feel like there are large gaps in the deck joint that do not have the screw/bolts.
Given that these are intended to be coastal cruisers and not world cruisers, I dont see it as a TERRIBLE design, rather something that should be kept in mind when buying a boat older than a few years.
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24-05-2019, 13:39
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#7
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֍֎֍֎֍֎֍֎֍֎
Join Date: Apr 2006
Posts: 15,136
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Re: New Beneteau's - How is the decks secured to the hull?
Dan-
Think about all the complaints you've heard about "can't get that goddamn 5200 off!". The material they use may not be 5200 but it is similar, it ain't budging if it was applied to clean surfaces. The mechanical fasteners are actually just there to hold the deck and hull together while the adhesive sets and cures, which can take a full week.
Remember that commercial airliners and combat aircraft have important bits like the wings GLUED on. It can work.
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24-05-2019, 13:40
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#8
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Senior Cruiser
Join Date: Mar 2003
Location: Thunder Bay, Ontario - 48-29N x 89-20W
Boat: (Cruiser Living On Dirt)
Posts: 49,082
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Re: New Beneteau's - How is the decks secured to the hull?
Note that the second link, for the Oceanis 38.1 (September 04, 2018), specified a “Hull-deck joint screwed, bonded ...” - no mechanical fasteners mentioned.
__________________
Gord May
"If you didn't have the time or money to do it right in the first place, when will you get the time/$ to fix it?"
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24-05-2019, 15:37
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#9
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Registered User
Join Date: Oct 2015
Posts: 2,007
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Re: New Beneteau's - How is the decks secured to the hull?
Quote:
Originally Posted by GordMay
“Our hull to deck joint with wide return flange is one of the strongest in the industry. It is chemically bonded (polyurethane mastic) with mechanical shear fasteners (screws and nuts/bolts) - 100%reliability with no recorded failure in millions of miles of tough ocean conditions.”
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I wonder... does the definition of "failure" include leaks? To me it does. But I am suspecting to Bendy-toy it does not.
There are lots of ways to build boats. More bad ones than good ones. Screws to secure deck to hulls--even if the are glued together with "polyurethane mastic"--doesn't cut it for me for anything except a day sailor.
I was shocked when I discovered that Catalina secured some of their stern pulpits to the hull with self tapping screws. The idea of a deck secured that way just boogles my mind.
But it IS cheap...
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24-05-2019, 16:34
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#10
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Registered User
Join Date: Jan 2015
Location: Seattle, WA
Boat: 1980 Pacific International Marine 41.5
Posts: 710
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Re: New Beneteau's - How is the decks secured to the hull?
@hellosailor - yes I would agree that 5200 or similar product is NOT going to come off. That **** is on there for a very long time if not forever. I am more concerned on long term horizon about leaks. My port lights were bedded with 5200. Those bastards were an incredible bear to get out, yet it was only 5 years ago when they were done. They had to be removed because they leaked.
5200 is an excellent adhesive, yet I question its sealant abilities. Having a deck joint sealed with something similar is fine, but if the external sealant fails, water will enter.
Aircrafts have a much better reputation with routine maintenance than the marine industry. Also they are bolted on aswell, not just glued.
@bill - that doesnt surprise me. These manufacturers are in an increasingly competitive industry. To operate a successful business they need to be as efficient as possible to get the boat down the line and onto the owner.
Not saying it's right but they are trying to reach a market of people that otherwise would not be reachable
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24-05-2019, 16:56
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#11
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Registered User
Join Date: Jan 2015
Location: Seattle, WA
Boat: 1980 Pacific International Marine 41.5
Posts: 710
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Re: New Beneteau's - How is the decks secured to the hull?
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24-05-2019, 17:13
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#12
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running down a dream
Join Date: Mar 2006
Location: Florida
Boat: cape dory 30 MKII
Posts: 3,105
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Re: New Beneteau's - How is the decks secured to the hull?
also when the stern deck to hull joint can be underwater .. like the picture shows .. you can assume the builder has taken the path of least resistance with construction.
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some of the best times of my life were spent on a boat. it just took a long time to realize it.
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24-05-2019, 17:16
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#13
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Moderator
Join Date: May 2008
Location: cruising SW Pacific
Boat: Jon Sayer 1-off 46 ft fract rig sloop strip plank in W Red Cedar
Posts: 21,134
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Re: New Beneteau's - How is the decks secured to the hull?
Quote:
Originally Posted by chowdan
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Interesting! The toe rail pic shows a bung. All very well, but what's under the bung? Self tapper or a proper screw/nut/backer? And in the last pic, is that u-bolt thing the "chain plate" for the split backstay as it appears? I'd wonder what structure is under the deck there, and how it distributes the stresses from the stay into the hull? Surely does not inspire great confidence in this observer!!
Jim
__________________
Jim and Ann s/v Insatiable II, lying Port Cygnet Tasmania once again.
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24-05-2019, 18:32
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#14
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Registered User
Join Date: Jan 2015
Location: Seattle, WA
Boat: 1980 Pacific International Marine 41.5
Posts: 710
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Re: New Beneteau's - How is the decks secured to the hull?
Quote:
Originally Posted by Jim Cate
Interesting! The toe rail pic shows a bung. All very well, but what's under the bung? Self tapper or a proper screw/nut/backer? And in the last pic, is that u-bolt thing the "chain plate" for the split backstay as it appears? I'd wonder what structure is under the deck there, and how it distributes the stresses from the stay into the hull? Surely does not inspire great confidence in this observer!!
Jim
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I believe they would be self tappers based on the link Gord provided.
On this boat, cleats are not on top of the toe rail, as such, the toe rail is just tapped in by screws(I assume).
The u-bolt is exactly what you thought it was - the "chain plate" for the split back stay. They use that design for all plates EXCEPT the fore stay - which is an actual stainless plate
I would love to see the under side structure aswell. Not of just the back stays, but of the shrouds as well.
Here are a few more photos - mid ship cleat(secured from under the deck) and shroud "chain plates".
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24-05-2019, 20:04
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#15
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Moderator
Join Date: May 2008
Location: cruising SW Pacific
Boat: Jon Sayer 1-off 46 ft fract rig sloop strip plank in W Red Cedar
Posts: 21,134
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Re: New Beneteau's - How is the decks secured to the hull?
Oh, my... this is on a 38 footer, isn't it? I guess that those u-bolts must work most of the time, and I'd hope that the shrouds are tied into a bulkhead or a knee that distributes stresses to both hull and deck, but, as I said, not confidence building for me. The rigs on Bennies don't seem to be falling over all the time, so they must be adequate. I wonder if the u-bolts are supposed to be replaced every 5 years like the brass through hulls?
The cleat doesn't look so badly done though. It's placed in the area where the deck overlies the inward-turning flange of the hull, and (if there is a decent backing plate) that's a pretty strong point to attach to. Lots of boats use such a scheme for deck cleats.
Jim
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Jim and Ann s/v Insatiable II, lying Port Cygnet Tasmania once again.
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