Muffler Support

[jackryan]

My boat had a piece of wood with a metal strap to support the mufflers. The wood has rotted out and the mufflers are just sitting on the bilge floor. It looks like Capt. Patrick used some kind of rubber strap to support the muffler in the rudder shelf building tips section. I was looking at the last photo in the following link: http://www.bertram31.com/proj/tips/rudder_shelf.htm

What is the best way to strap down the muffler and what kind of support do I need for the exhaust hose running from the muffler to the stern?

Thanks for all of the help,

JR

[CaptPatrick]

On the current boat, I used two pieces of 1/8" rubber sheeting per tie down with 1/8" fiberglass plate as washers for the #8 screws...

Rubber sheating was procured through McMaster-Carr.

[coolair]

You never stop amazing me! Everything you make is art!
but i got a question. ON the rudder shelf build tips, you say use roving, they guys at the fiberglass shop say use mat, because its much harder to use the roving, will mat work?

[CaptPatrick]

Roving isn't hard to work with, especially on a flat surface. The roving has far more strength and rigidity as a middle ply. Mat is fine for the outside encasement. You can also use 45º/45º biaxle as the middle ply.

It takes an awful lot of 1 1/2 oz mat to make up the equivalent fiber content of roving and mat will take almost twice the amount of resin than does roving. There a stitched on mat backed roving called fabmat that helps control some of the raveling around the edges that is persistent with just straight roving.

[coolair]

Ya, Thats kinda what I was thinkin, Is the wroven better as the middle or the 1708 as teh middle? ON your builders tips you say wroven in the middle and 1708 on the outside.

[jackryan]

Capt. Patrick,

Very impressive. Thanks. Did the rubber bungee system work well? (Picture from building tips section on composite rudder shelf)

Thanks,

JR

[CaptPatrick]

Jack,

Yup they work just fine, but because they're bungies, designed to stretch, I figure that sooner or later they might get a bit loose. No problem with re-tensioning them or replacing, but I think that the rubber sheeting will still be doing the job longer than the bungies. The bungies are less expensive and available at just about every box & hardware store around.

6 of one half a dozen of the other...

[jackryan]

Thanks Capt. Patrick,

We ended up going with the Coosa board for the rudder shelf. I think it's going to work out great. We also used Coosa for the sub flooring below the lower helm. The windows had leaked so much water onto the teak and holly flooring over the years that the plywood sub floor had gone bad. There is also a small bilge bulkhead that separates the v-birth from the main cabin. There was a strip of wood attached to this bulkhead that held the v-birth flooring up. This strip gave way yesterday, so I think I'm going to have to use some Coosa to create a new bulkhead there. The A/C sea strainer and the A/C pump are also attached to the bulkhead.

I checked the price of 1/2" Okoume plywood and it was nearly as much as the 5/8 Coosa. I got the 5/8 Coosa for $179.00 for a 4X8 sheet and the Okoume was $140.00 per sheet.

Thanks again for all the help,

JR

[CaptPatrick]

The A/C sea strainer and the A/C pump are also attached to the bulkhead.

If those two items are on that little fwd partition bulkhead, they're waaaayyyy to far forward...

Your a/c intake and the pump should be no farther forward than just forward the cabin/engine bulkhead to keep from loosing a prime when you're running. You can mount the pump further forward if necessity dictates, but the intake through hull has to amidships or aft.

I would strongly recommend putting an external strainer on the intake and getting rid of the internal strainer all together. Better use of space and less maintenance.

[jackryan]

Thanks Capt. Patrick,

We're going to address those issues when we take the bulkhead out this morning.

JR

[Marlin]

I installed 2 new 6" mufflers to cradles I fabricated out of 2 pcs of 3/4 coosa epoxied together that I epoxied to the hull. I then strapped the mufflers to the cradles with an 8" aeroclamp that I made by cutting the tightening screw section off about 1" from the screw assy. Took an awl and punched a hole in this section and a hole in the longer section away from the helical grooves, ran a 3" ss screw thru each part ,tightened the clamp to the helical grooved section like you tighten a hose clamp. I have {per Capt Pat's advice} a section of hose aft of the muffler as well as the hose leading from the engine, no vibration to worry about, maybe another method