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Author Topic:   Boston Whaler, Hull to deck joints

alexhiguera posted 03-02-2005 12:53 AM ET (US)
How the BWhalers have been joined (kull and deck) in all of their production years?
I have an 1987 Outrage 18', a friend has a 1970's 15' sport and both are joined by fusion (fiberglass resin I guess) of the deck and hull.
I heard another friend say that early Whalers were not a one piece design.
Have they used diferent methods over the years of joining hulls to make BWhakers a "one piece construction"?
alexhiguera posted 03-02-2005 01:05 AM ET (US)
The friend that said that early whalers were not a one piece design, said they used to be bolted together.
Can anyone prove him wrong with a pic of a realy early hull?
Tom W Clark posted 03-02-2005 01:37 AM ET (US)
Alex,
Your friend is wrong. All Unibond Whaler hulls have their two skins joined with what Whaler calls "The Weld" where the uncured 'glass and resin from the lay-up of the inner and outer hulls are sandwiched together.
This "weld" is basically a lap joint that cures into a monolithic joint between the two skins.
I cut up an early 13 foot Whaler for fun some time ago. The "weld" at the transom was a bit more involved as the plywood has to be accommodated as well, but the 'glass cloth still inter-folds in a thick build up of fiberglass.
Historically the joint at the transom was then detailed by hand (after the hull was removed from the molds) to remove just enough gel coat to expose the resin beneath. Gel coat would actually be added as touch up if needed to get a nice even line across the transom where no rub rail would cover it.
This joint was called the "green line" and it was a point of pride with Whaler to leave it for the world to see.
The "green line" only appears on the small whalers up to the 16' 7" hulls and is only seen on those hulls produced until the early 1990s. Since then Whaler has adopted the labor saving (read: cost cutting) detail of simply running a rub rail across the transom joint or covering the joint with an aluminum extrusion.
dfmcintyre posted 03-02-2005 05:50 AM ET (US)
Tom -
There might be some confusion here. Wasn't the early 21' Outrage dump truck sided hull bolted at the rubrail?
Don
jimh posted 03-02-2005 08:49 AM ET (US)
I agree with Tom on the "point of pride" notion. On a 1976 SPORT 15 I used to own the green line joint was beautiful. I buffed, polished, and waxed it to a high gloss. It was another of the many fine details of classic Boston Whaler boats which made them stand far above the crowd.
Here is a classic Boston Whaler hull-deck joint without any sign of mechanical fasteners. This is from a 1976 15-foot hull.
http://continuouswave.com/whaler/reference/images/greenLine1976.jpg
alexhiguera posted 03-02-2005 09:58 AM ET (US)
Tom, DF, JIM, I new this was a kind of "weld" but didn't know it was done by setting the two parts together before complete curing, for then their resins would combine as one.
So the deck part was popped out of the mold without being cured and set on top of the hull part which was still in its mold to retain its shape. This is the only way I see it, so that it doesn't cure twisted or binded one of the parts had to remain in its mold.
Am I right in my guess about how it was done?
I have also heard that most all boats now are being fabricated this way.

And then how was the foam injected, any specific points/areas where they drilled into, injected and then re-gelcoated?
Tom W Clark posted 03-02-2005 10:36 AM ET (US)
Don,
The Outrage 21 had its deck bolted to the hull, but the deck mold was a separately molded third component. We are talking about the hull itself. Imagine the Lo-Profile 19's hull. No bolts there. But I agree, this might be how Alex's friend got confused.
Alex,
The inner hull is not "popped out" of the mold and then joined to the lower hull. The inner hull mold is inverted and lower onto the lower hull's mold and the two steel molds are bolted together.
At that point the liquid foam is poured into the hull cavity through the "Sprue Hole", which is usually seen in the bottom of the bow locker on small Whalers, and out of sight in the fuel tank cavity on larger Whalers.
The foam expands with tremendous pressure which is why the molds need to be super strong and be clamped together.
Whaler's own literature offers some glimpses and description of this process. For example, see page 5 of the 2003 Boston Whaler catalog for some photos of the hull molds being brought together.
It's interesting to note that the same process Dick Fisher developed in the mid 1950s is still being used today. No other boat manufacturer uses this complex process.
tuna1 posted 03-02-2005 03:13 PM ET (US)
That joint is a weak spot in the design,IMHO.Every whaler i have removed the rub rail from i have seen areas where that joint has opened.In most cases a slight damage area on the rub rail will match a cracked/open joint area on the hull.The joint is Verticle and when opened it allows water to enter and then compromise the foam and joint further.
I also have a dealer display of the crosssection of the hull,at the deck/hull joint on the sample it has opened completely with time. The sample is over 10 years old.Also on the sample the hull bottom laminate has separated away from the foam core.
IMHO the design of the joint is a compromize,and like any thing it's not perfect.I also have a Yankee Voyager and i firmly believe it was a design exerzise to develop new design processes and they just ran out of money to proceed with it.The foam grid system used in the hull instead of a wood stringer system is and was a step into the future.
alexhiguera posted 03-02-2005 04:43 PM ET (US)
I have myself a 18' Outrage 1987 in near perfect condition always dry used/covered, raised in davits. Take care of it more than I take care of myself.

The boat I'm working on right now is a 15' super sport 1984, Evinrude 65 Commercial in 1998. This last one has failure points behind the rub rail that I'm replacing as you said tuna 1. Delamination of hull and deck joint not all but a few spots.
It has been dry used and covered, raised in davits all his life but the simple stuff neglected and almost all the deck/floor is soggy/wood rot under.
The simple stuff is sealing attached hardware with any silicone or polyurethane sealant, this was not done right and used like this for many years, now that I'm working on it I can explain to the owner why none of the screws hold to the deck, anywhere.
I will try my best (filling and saturating with epoxy the core), but cutting out the floor to replace the ply, nonskid and gelcoating the whole deck is not in the budget as it will be sold hopefully by the end of the year.
Great boats... dry used (trailer or davits) - a tube of sealant and common sense = crap!
LHG posted 03-02-2005 05:21 PM ET (US)
I have determined that on the ribbed 21's, the top hull mold (which contains the ribs) is primarily glued on, with 5200 adhesive. On the inside of the boat, this adhesive is in abundant, clear evidence, around the entire perimeter. From what I can tell, the bolts were a secondary precaution, probably a back-up mechanical connection in case the glue didn't hold. But as we all know about 5200, it did. The bolts look great, but from what I can tell, are not needed. With the re-design to the 1973 smoothsides, this is confirmed, as no bolts are used.
dfmcintyre posted 03-02-2005 08:46 PM ET (US)
Larry -
Small nit....but was 5200 around (even for factories) 35 years ago?
D

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Author	Topic: Boston Whaler, Hull to deck joints
alexhiguera	posted 03-02-2005 12:53 AM ET (US) How the BWhalers have been joined (kull and deck) in all of their production years? I have an 1987 Outrage 18', a friend has a 1970's 15' sport and both are joined by fusion (fiberglass resin I guess) of the deck and hull. I heard another friend say that early Whalers were not a one piece design. Have they used diferent methods over the years of joining hulls to make BWhakers a "one piece construction"?
alexhiguera	posted 03-02-2005 01:05 AM ET (US) The friend that said that early whalers were not a one piece design, said they used to be bolted together. Can anyone prove him wrong with a pic of a realy early hull?
Tom W Clark	posted 03-02-2005 01:37 AM ET (US) Alex, Your friend is wrong. All Unibond Whaler hulls have their two skins joined with what Whaler calls "The Weld" where the uncured 'glass and resin from the lay-up of the inner and outer hulls are sandwiched together. This "weld" is basically a lap joint that cures into a monolithic joint between the two skins. I cut up an early 13 foot Whaler for fun some time ago. The "weld" at the transom was a bit more involved as the plywood has to be accommodated as well, but the 'glass cloth still inter-folds in a thick build up of fiberglass. Historically the joint at the transom was then detailed by hand (after the hull was removed from the molds) to remove just enough gel coat to expose the resin beneath. Gel coat would actually be added as touch up if needed to get a nice even line across the transom where no rub rail would cover it. This joint was called the "green line" and it was a point of pride with Whaler to leave it for the world to see. The "green line" only appears on the small whalers up to the 16' 7" hulls and is only seen on those hulls produced until the early 1990s. Since then Whaler has adopted the labor saving (read: cost cutting) detail of simply running a rub rail across the transom joint or covering the joint with an aluminum extrusion.
dfmcintyre	posted 03-02-2005 05:50 AM ET (US) Tom - There might be some confusion here. Wasn't the early 21' Outrage dump truck sided hull bolted at the rubrail? Don
jimh	posted 03-02-2005 08:49 AM ET (US) I agree with Tom on the "point of pride" notion. On a 1976 SPORT 15 I used to own the green line joint was beautiful. I buffed, polished, and waxed it to a high gloss. It was another of the many fine details of classic Boston Whaler boats which made them stand far above the crowd. Here is a classic Boston Whaler hull-deck joint without any sign of mechanical fasteners. This is from a 1976 15-foot hull. http://continuouswave.com/whaler/reference/images/greenLine1976.jpg
alexhiguera	posted 03-02-2005 09:58 AM ET (US) Tom, DF, JIM, I new this was a kind of "weld" but didn't know it was done by setting the two parts together before complete curing, for then their resins would combine as one. So the deck part was popped out of the mold without being cured and set on top of the hull part which was still in its mold to retain its shape. This is the only way I see it, so that it doesn't cure twisted or binded one of the parts had to remain in its mold. Am I right in my guess about how it was done? I have also heard that most all boats now are being fabricated this way. And then how was the foam injected, any specific points/areas where they drilled into, injected and then re-gelcoated?
Tom W Clark	posted 03-02-2005 10:36 AM ET (US) Don, The Outrage 21 had its deck bolted to the hull, but the deck mold was a separately molded third component. We are talking about the hull itself. Imagine the Lo-Profile 19's hull. No bolts there. But I agree, this might be how Alex's friend got confused. Alex, The inner hull is not "popped out" of the mold and then joined to the lower hull. The inner hull mold is inverted and lower onto the lower hull's mold and the two steel molds are bolted together. At that point the liquid foam is poured into the hull cavity through the "Sprue Hole", which is usually seen in the bottom of the bow locker on small Whalers, and out of sight in the fuel tank cavity on larger Whalers. The foam expands with tremendous pressure which is why the molds need to be super strong and be clamped together. Whaler's own literature offers some glimpses and description of this process. For example, see page 5 of the 2003 Boston Whaler catalog for some photos of the hull molds being brought together. It's interesting to note that the same process Dick Fisher developed in the mid 1950s is still being used today. No other boat manufacturer uses this complex process.
tuna1	posted 03-02-2005 03:13 PM ET (US) That joint is a weak spot in the design,IMHO.Every whaler i have removed the rub rail from i have seen areas where that joint has opened.In most cases a slight damage area on the rub rail will match a cracked/open joint area on the hull.The joint is Verticle and when opened it allows water to enter and then compromise the foam and joint further. I also have a dealer display of the crosssection of the hull,at the deck/hull joint on the sample it has opened completely with time. The sample is over 10 years old.Also on the sample the hull bottom laminate has separated away from the foam core. IMHO the design of the joint is a compromize,and like any thing it's not perfect.I also have a Yankee Voyager and i firmly believe it was a design exerzise to develop new design processes and they just ran out of money to proceed with it.The foam grid system used in the hull instead of a wood stringer system is and was a step into the future.
alexhiguera	posted 03-02-2005 04:43 PM ET (US) I have myself a 18' Outrage 1987 in near perfect condition always dry used/covered, raised in davits. Take care of it more than I take care of myself. The boat I'm working on right now is a 15' super sport 1984, Evinrude 65 Commercial in 1998. This last one has failure points behind the rub rail that I'm replacing as you said tuna 1. Delamination of hull and deck joint not all but a few spots. It has been dry used and covered, raised in davits all his life but the simple stuff neglected and almost all the deck/floor is soggy/wood rot under. The simple stuff is sealing attached hardware with any silicone or polyurethane sealant, this was not done right and used like this for many years, now that I'm working on it I can explain to the owner why none of the screws hold to the deck, anywhere. I will try my best (filling and saturating with epoxy the core), but cutting out the floor to replace the ply, nonskid and gelcoating the whole deck is not in the budget as it will be sold hopefully by the end of the year. Great boats... dry used (trailer or davits) - a tube of sealant and common sense = crap!
LHG	posted 03-02-2005 05:21 PM ET (US) I have determined that on the ribbed 21's, the top hull mold (which contains the ribs) is primarily glued on, with 5200 adhesive. On the inside of the boat, this adhesive is in abundant, clear evidence, around the entire perimeter. From what I can tell, the bolts were a secondary precaution, probably a back-up mechanical connection in case the glue didn't hold. But as we all know about 5200, it did. The bolts look great, but from what I can tell, are not needed. With the re-design to the 1973 smoothsides, this is confirmed, as no bolts are used.
dfmcintyre	posted 03-02-2005 08:46 PM ET (US) Larry - Small nit....but was 5200 around (even for factories) 35 years ago? D