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Author Topic:   engine splashwell bulkhead - hollow or solid?
bigjohn1 posted 04-06-2006 10:29 PM ET (US)   Profile for bigjohn1   Send Email to bigjohn1  
Regarding an '05 170 MONTAUK, I hope I am using the correct terminology for this location of my boat but I'm not sure. The location is the forward bulkhead of the engine splash well. I know there is no wood embedded there but I'm wondering what the construction method for this "wall" is. Is it foam-filled or hollow? It is simply two section of raw fiberglass (with a gelcoat layer) and a void in between?

I am working with a marine fabricator in the design of a high-strength rod holder system and he wants to use this surface as supplemental mounting point. It will NOT be a primary load-bearing surface but will take a little stressing via a 12" x 14" aluminum plate which will be thru-bolted, have a backing plate on the rear side, and have bolts which will be run thru machined sleeves to prevent cracking the bulkhead. The transom and rear corners of the boat (where wood and phenolic are embedded) will be the primary load-bearing surfaces. This forward bulkhead will "tie" the two sides togther and prevent vibration.

On the construction of this section, I presume Whaler would have followed earlier construction methods for older models....but I'm not entirely sure.

Chuck Tribolet posted 04-06-2006 10:51 PM ET (US)     Profile for Chuck Tribolet  Send Email to Chuck Tribolet     
I'll bet a beer it's full of foam.

Here's my logic:

Whaler builds the turtle using a mold. They spray gelcoat,
resin, add glass (either chopper or fabric). At the same
time they are are making the hull. Then they glue the hull
and turtle togther, and fill them with foam. What would
keep the foam out?

And there's no structural reason to make it solid glass.

So if you want a strong mounting point there, just do the
West System hockey puck.


Tom W Clark posted 04-07-2006 01:53 AM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
Whaler hulls are usually completely filled with foam between the two skins. The exception to this are what Whaler calls "close-outs", which the Montauk 170 does have in the general area you describe.

Close-outs allow for mechanical rigging in small, otherwise inaccessible spaces. They are created by laminating a plastic or 'glass shell to the backside of the interior hull skin before the inner and outer skins are clamped together and filled with foam.

Reading your post I am unclear exactly what area you are asking about so the answer (for now) is that there may, or may not be foam there.

Backlash posted 04-07-2006 08:17 AM ET (US)     Profile for Backlash  Send Email to Backlash     
If I'm not mistaken, haven't there been prior posts here regarding mounting stero speakers in this forward bulkhead? As I recall this area was hollow - allowing speaker wires to be run to the center console.
erik selis posted 04-07-2006 10:00 AM ET (US)     Profile for erik selis  Send Email to erik selis     

I took pictures of the inside of the access hole, to the starboard of the slashwell a couple of years ago. Here's a link: 170%20Montauk%20Erik%20features/Graphic6.jpg

IMO the area you are talking about is part of the hull and is filled with foam. It is covered by fiberglass layers that's part of the splashwell and the front of the steps.

Hope this helps.


Backlash posted 04-07-2006 12:14 PM ET (US)     Profile for Backlash  Send Email to Backlash     
I was thinking of the Nantucket NOT the 170 Montauk.
Bulldog posted 04-07-2006 01:57 PM ET (US)     Profile for Bulldog  Send Email to Bulldog nice pictures this site is amazing! I am also of the thought that it is foam filled and there is a possibilty that there is a backer board there also. My 1987 20' Hull has a 1/2" piece of plywood ,one is 5" and the other is 6" high full width embedded on both sides off the splash well forward wall. Have you checked a wood or backing drawing from Whaler.....Jack
bigjohn1 posted 04-08-2006 09:31 AM ET (US)     Profile for bigjohn1  Send Email to bigjohn1     
Thanks for the great replies!

Tom, if you were sitting at the helm of a 170 facing aft looking at the motor, it would be the horizontal bulkhead that lays perhaps 8-10" forward of the engine mounting bolts in the transom.

Eric - thank you for the picture, I think that is the only one I have seen on this site depicting the 170 MONTAUK. It does give me an idea of what it looks like under there.

Chuck, I am following up on an idea you gave me some months back on this rod holder system. It was your idea to try something with the transom utilizing the engine mounting bolts. As it turns out, my fabricator seconds that idea and is trying to improve upon the integrity of that basic idea. He wants to "tie" (weld) the two sides together by utilizing this splashwell bulkhead. "Tieing" the two sides together will prevent vibration. Wahoo are very difficult to boat without keeping the boat in forward gear during the fight. We bring them in doing about 3-4 knots; you're cranking them on a Shimano Tiagra 80 and short bent-butt rods. In this situation, its all about structural integrity with a rod holder.

Forgive the rookie question but what is the West System hockey puck?

Tom W Clark posted 04-08-2006 11:09 AM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     

The area you describe, identified in this photo as "Splash-well front panel" is foam filled without wood backing:

bigjohn1 posted 04-12-2006 07:21 AM ET (US)     Profile for bigjohn1  Send Email to bigjohn1     
Tom, thanks very much.

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