Wet Through-hull Exhaust Question

[iqxoqlms]

I am in the process of resotring an old Ski Supreme and have a question about the exhaust. On my model the exhaust runs under the deck (outboard of the stringers). I am in process of replacing the deck and stringers so when the exhaust goes back in I want it to be 100%. I'd hate to have to cut the floor up in the future due to problems.

I plan to replace the rubber exhaust hose and double clamp all connections. My question relates to one of the tips. It appears that heat got to it at one point and it has melted - forming a bit of a cone. I cut off about 1/2" of the tip to get rid of the worst of the melted plastic. The problem is that the conical shape of what is left does not work well for clamping the hose securely. Can i build up the ouside of the tip with epoxy mat and resin to make it straight again and maybe form a lip to prevent it from sliding off? I have attached a couple of pictures of what I am dealing with. I am trying to keep cost low on this project and am surprised by the cost of these pieces if I need to replace them. All suggestions appreciated!!!

 

[Philster]

Re: Wet Through-hull Exhaust Question

Couple of screws should work. What is the temp of the tips vs epoxy/resin?

 

[iqxoqlms]

Re: Wet Through-hull Exhaust Question

Thanks for the reply. That is my primary concern too...would epoxy resin/fiberglass hold up to the heat produced.

I had considered the screw idea as well. Seal it up real well with high temp sealant and put 4 screws in, plus the clamp(s). I'd still like to have a flat surface for the clamp to land on and I can't put it all the way to the tip as there is no clearance through the transom - the clamp has to ride at least 3/4" forward of the mounting surface on tip which gets me into the "cone". Obviously this sits below the water line so making it water tight is one of my major concerns.

 

[Don S]

Re: Wet Through-hull Exhaust Question

Replace them. The fact that they are at or below the water line means you are flirting with disaster. (sinking) if your repairs fail.
Do a google search on Thru Hull Exhaust Fittings and see what you come up with.

 

[iqxoqlms]

Re: Wet Through-hull Exhaust Question

Bubba:

Great idea! If need be I can always shorten up the rubber connector hose which is currently 8" - 10" long. Is there a variety of PVC that handles heat bettern than another?

Mark

 

[funk6294]

Re: Wet Through-hull Exhaust Question

I know you wanted to keep cost low on this project, but have you checked ebay? There are several pairs on their and not sure if these would fit you app, but there is a pair on their for 39.99. Might be worth replacing it now, instead of having to cut back inot it to fix it again later.

http://cgi.ebay.com/ebaymotors/MARINE-BOAT-THRU-HULL-EXHAUST-TIPS_W0QQitemZ200435734588QQcmdZViewItemQQptZBoat_Parts_Accessories_Gear?hash=item2eaae6983c

 

[iqxoqlms]

Re: Wet Through-hull Exhaust Question

I agree - I want to put it together in a manner that allows me not to worry about it again (or rip up my new deck to make repairs). I did see that set on eBay but I need 3" diameter.

Thanks to all of you for your assistance. I have found a pair for $100 on line (so far).

Decisions...decisions.

 

[salty87]

Re: Wet Through-hull Exhaust Question

you could leave access to the exhaust at the transom. some of the 80's supra inboards are like that. the deck stops about a foot from the transom. a small bulkhead between the stringers keeps water from getting to the foam.

either way, don't skimp on parts for below the waterline. are you adding drainage when you rebuild?

 

[havasuboatman]

Re: Wet Through-hull Exhaust Question

Dude, are you insane? You want to Mickey Mouse a plastic part of your boat's exhaust, a part that is already known to be heat effected and heat damaged, that goes thru the hull, below the waterline, and then bury it under the deck where you can't check on it?
You want to do this to save money?

I'm sorry, but you guys giving him suggestions that don't end in "replace those tips", should be ashamed of yourselves.
Glue? PVC elbows?

 

[havasuboatman]

Re: Wet Through-hull Exhaust Question

You are right, it is plastic, ABS though, not PVC. (I'll send you an address to mail that weeks paycheck to ) and was used in place of aluminum or SS to cut costs when the boat was originally built.
It's already melted once and that was with the exhaust traveling in a straight line.
You never,ever, use a plastic or rubber elbow on a boats exhaust. PERIOD. The first time the impeller fails, the exhaust will immediately burn right thru the elbow and his boat will sink.
The hose clamps should never be made inaccessable. Leave a cut out as stated in another post. Also there should also be two clamps on each hose end.

 

[Fun Times]

Re: Wet Through-hull Exhaust Question

Here is another place you can order 3.5 inch exhaust parts from.
New parts are cheap compared to the cost of labor of collecting your boat of the bottom of the lake.

http://www.eddiemarine.com/store/cart.php?m=product_detail&p=11449&c=60

http://www.eddiemarine.com/store/cart.php?m=product_list&c=61

http://www.eddiemarine.com/store/cart.php?m=product_list&c=58

http://www.eddiemarine.com/store/cart.php?m=product_list&c=59

http://www.eddiemarine.com/store/cart.php?m=product_list&c=7

 

[salty87]

Re: Wet Through-hull Exhaust Question

running the exhaust above the deck would require 2 elbows. the risers are positioned to direct the exhaust below deck. so, you'd need an elbow to get it above deck and then another to exhaust it below the waterline. not to mention it would prob require a re-design of the rear seats or storage to accomodate a hot exhaust pipe.

this is a link to 3" ss tips.... http://skidim.com/prodinfo.asp?number=SSI03-3109090

skidim is a great place to get parts for tournament inboards.

 

[iqxoqlms]

Re: Wet Through-hull Exhaust Question

Thank you all for your input and opinions. I got what I asked for...advice and suggestions. I will research replacement pieces.

 

[havasuboatman]

Re: Wet Through-hull Exhaust Question

Thank you all for your input and opinions. I got what I asked for...advice and suggestions. I will research replacement pieces.

Wise choice

 

[havasuboatman]

Re: Wet Through-hull Exhaust Question

Um, aren't you forming an elbow with the hose??? Its one time we will agree to disagree.

There is the small matter of a weeks pay, Bubba... Will you drop it in the mail?

 

[iqxoqlms]

Re: Wet Through-hull Exhaust Question

I have the whole boat torn apart right now. here are a couple that show how it was set up. One option I have is bringing the exhaust inside the stringers (that is how it was done on Ski Supreme models a few years newere than this one). That would include fiberglassing the existing holes shut and opening new ones. Not overly excited about doing that - and I would have to mess with cross memeber fabrication, steering cable mounts, etc.

 

[salty87]

Re: Wet Through-hull Exhaust Question

to quote bubba....wow!

i agree. that's a crazy set-up with the exhaust hose clamping under the deck. here's a few pics of supra exhaust. there's about a 45 degree bend in the pipe to match the riser angle and so you can service the clamps above the deck...the pipes go through the transom, no clamps or connections under the deck...

another shot with most of it back together...

 

[salty87]

Re: Wet Through-hull Exhaust Question

one more pic. this is the rear of another supra. the rear storage locker and gas tank have been removed. the tank straddles the stringers. this model supra has mufflers, mine does not.

you can see the deck doesn't go all the way back to the transom. i didn't re-build mine this way, i hadn't seen the pic until after i was finished. if i had seen it sooner, i would have done the same. it's not uncommon for older supra's to leak at that the exhaust ports and swim platform bolts wetting the foam. having access to all of the transom hardware and rudder is niiiice.

 

[iqxoqlms]

Re: Wet Through-hull Exhaust Question

I will look into this as well. I did pick up new tips yesterday - the old heat stressed pieces are being discarded. The deck does not extend to the transom - there is about 12" of open space behind the rear seat/under the fuel tank. I can access the connections made there. The connection to the front of the fiberglass resonators cannot be accessed (as the boat was built originally) without pulling up the deck. I looked at Salty87's build and liked the straight pipe idea with connections from the manifolds to the pipe made above deck. Considering the time I am spending on this restoration I don't want to be tearing up the deck for a part failure.

Again - thanks for all of the suggestions!!

 

[iqxoqlms]

Re: Wet Through-hull Exhaust Question

Yup - I intended to have the connection from manifold to pipe made above deck. Are you suggesting that a stainless flange be welded to the stainless pipe at the trasom to connect/seal it as it passes through? This would elimante the use of tips altogether. The only clamp fitting would then be on the one foot (or less) length of hose between the manifold and the new stainless pipe.

I think it is very common for these ski boats to have clamped exhaust connections below the water line - but certainly would be concerned to have a 4" hole opened up in the transom while on the water. I am not aware of a pump that would keep up with that to get you back to the dock!