Mahe 36: Adding cooling thru hulls

[Rufduck]

Have decided to add a pair of engine cooling thru hulls , bypassing the sail drive leg ones. Like others my legs are partially occluded with muscles and reduced water flow leading to high running temperatures (200f+ at 2200+). They cannot be cleaned from the top (there is a metal deflector plate at the bottom of the existing sea cock and reaming the leg from the bottom in 48*f water every six months is unsatisfactory.
Using Groco 3/4” flanged seacock with BB-1 backing plates. Plan to install just aft of the rear engine/drive mount ahead of the muffler. It fits and is protected to some degree.
Question: the engine saddle is bonded to the hull and the thru hull will penetrate both.
Does anyone know how secure that bond is? OR am I likely to find a void between the two structures?
Does anyone know how thick the hull is in this area?
Has anyone done this modification?
Is there a better location for the seacock and if so, where?
Any help appreciated.
Cheers, Rufduck

[Kazamaran]

Hello Rufduck. Good idea.... I've sounded the saddle on occassion. Its thick but has voids; side towers, etc. I'm not sure if the bottom sits flush with the hull or how they mounted before glassing in. My vote on the mount would be off to the side, forward of the prop a bit. Generally out of the slip stream. The sail drive is designed to provide water unimpeded by cavitation so I think next best thing is anywhere where current and cavitation are least likely. Good luck. Would like to hear how this all goes.
Capt Kaz

[Rufduck]

Inboard or outboard? Kinda ruled that out as really tight and where I wedge my size 16 feet when servicing engine. Will look again. Best location purely for smooth water is ahead of the engine in the bilge but nearly impossible to access if ever the need arose (let alone to install). Thnx

[redneckrob]

Originally Posted by Rufduck

Inboard or outboard? Kinda ruled that out as really tight and where I wedge my size 16 feet when servicing engine. Will look again. Best location purely for smooth water is ahead of the engine in the bilge but nearly impossible to access if ever the need arose (let alone to install). Thnx

My generator intake is forward of the engine about a foot to the right of centerline up the starboard (inboard) side of the hull (in the port hull). It has decent access, certainly better than if it was at the bottom of the bilge. I can run the generator fine when underway with engines, but it's just a little Nextgen 3.5 so probably a lot less water than the engines would need.

Also interested in hearing back what you end up doing. I've had the same issue requiring a dive for the past two years. I need to remember to do it in the fall this year so I won't be blocked in the spring when the water is still cold!

[Kazamaran]

Tough one anyway you cut it. Think I would go outboard side. How about in front of rudder post? Move bilge pump over.

[Rufduck]

Last time out we ran both D1-30B engines at sustained 2600-2700 RPM. Both temperatures were elevated to 200*+ and remained so even at reduced power, <2000 RPM. The raw water pickup in the saildrive leg has been problematic for the last three years with muscle growth internally. Cleaning is only feasible from in the water as a baffle plate separates the leg from the seacock. I made the decision to install a tandem pickup for each engine.

Original plan was to install one for each engine but on the 4 hour run to the haul out, only the port engine misbehaved, so decided to only do the port engine and evaluate to see if it makes a significant difference.

Choosing location. At first I planned to install just aft of the rear saildrive mount. Two problems…just barely enough room for the backing block and there appeared to be a significant void between the engine mount saddle and the hull.
I chose to locate it just beside and slightly forward of the rudder post on the inboard side. It misses the grounding plate and appeared to be in a location where the saddle and hull appeared to mate well. Preliminary figment of assembled seacock gave ample room for access and movement of the shutoff handle. The location was marked and indexed.

I used a disc angle grinder to prep the surface of the saddle and a 1 1/8” hole saw to bore the hole. There was a 3/16 deep void between the two surfaces that I filled with 6-10 thickened epoxy and let cure. The next day I finished drilling the hole.
I prepped the bottom by making a round sanding mandrel that fit in the hole and was slightly larger than the OD of the bronze mushroom head. Ground off the anti foul. Trial fit the assembly.

Final assembly. I completely assembled the seacock, backing block, 3/4 bronze barb fitting using 4200 as the inside sealant between the backing block and the seacock. Bolts with washer and lock washer tightened.
I decided not to gamble that I could assemble everything with the 6-10 adhesive and the 4200 mushroom sealant at the same time. So, I wrapped Teflon pipe tape on all the through hull threads except the last 3/4”. The tape would preclude the epoxy from binding the threads of the mushroom to the seacock if there was too much squeeze out. Linda fed the mushroom and tightened as I held the seacock assembly. Let cure at 80*f.
Next day she unscrewed the through hull and I’m glad I added the Teflon tape as the squeeze out contacted the threads.
Applied 4200 to the mushroom and plenty on the shank and screwed into the hole in the hull.

I sourced a length of 3/4” ID spiral reinforced vinyl hose and found that 30” is ample. I also found a pair of 306 stainless 3/4 barb tees (later found the same in bronze) and inserted into the existing pickup hose from the old seacock to the strainer. Coupled the new seacock to the branch.

I chose Groco based on recommendations from some whose opinions I respect. I was satisfied with the prices from Defender (east coast US). The ss tee came from Amazon. They are for the commercial food and beverage industry and appeared well made. I was stuck for screw clamps as all mine were fractionally too small. They will be replaced with HPS 27-16 3/8” wide embossed clamps as the 1/2” wide ones are too wide.

The stbd engine bay has the hot water tank and hose for the shower along with some other clutter. However, I don’t foresee any major problems installing the second one in the same relative position (inboard and just ahead of the rudder post) if I deem it necessary.

An upside is that I have discovered a new contortion that allows access to the forward part of the engine 😃

I apologize for the orientation of the pics. Don’t know how to correct. Any questions please ask.
Cheers,
Rufduck

[Kazamaran]

Rufduk. Great job. Looks like you put some real thought into your design. I know you were anxious about it. Can't blame you. Hard to put holes in a perfectly good hull. I'd be interested in how your engine temp responds. I had an over heating issue last week at 2100 rpm. Sea strainer totally blocked with a sea snake!!!! What's the fix for that?! Anyway, good luck. Capt Kaz

[redneckrob]

Originally Posted by Rufduck

Last time out we ran both D1-30B engines at sustained 2600-2700 RPM. Both temperatures were elevated to 200*+ and remained so even at reduced power, <2000 RPM. The raw water pickup in the saildrive leg has been problematic for the last three years with muscle growth internally. Cleaning is only feasible from in the water as a baffle plate separates the leg from the seacock. I made the decision to install a tandem pickup for each engine.

Original plan was to install one for each engine but on the 4 hour run to the haul out, only the port engine misbehaved, so decided to only do the port engine and evaluate to see if it makes a significant difference.

Choosing location. At first I planned to install just aft of the rear saildrive mount. Two problems…just barely enough room for the backing block and there appeared to be a significant void between the engine mount saddle and the hull.
I chose to locate it just beside and slightly forward of the rudder post on the inboard side. It misses the grounding plate and appeared to be in a location where the saddle and hull appeared to mate well. Preliminary figment of assembled seacock gave ample room for access and movement of the shutoff handle. The location was marked and indexed.

I used a disc angle grinder to prep the surface of the saddle and a 1 1/8” hole saw to bore the hole. There was a 3/16 deep void between the two surfaces that I filled with 6-10 thickened epoxy and let cure. The next day I finished drilling the hole.
I prepped the bottom by making a round sanding mandrel that fit in the hole and was slightly larger than the OD of the bronze mushroom head. Ground off the anti foul. Trial fit the assembly.

Final assembly. I completely assembled the seacock, backing block, 3/4 bronze barb fitting using 4200 as the inside sealant between the backing block and the seacock. Bolts with washer and lock washer tightened.
I decided not to gamble that I could assemble everything with the 6-10 adhesive and the 4200 mushroom sealant at the same time. So, I wrapped Teflon pipe tape on all the through hull threads except the last 3/4”. The tape would preclude the epoxy from binding the threads of the mushroom to the seacock if there was too much squeeze out. Linda fed the mushroom and tightened as I held the seacock assembly. Let cure at 80*f.
Next day she unscrewed the through hull and I’m glad I added the Teflon tape as the squeeze out contacted the threads.
Applied 4200 to the mushroom and plenty on the shank and screwed into the hole in the hull.

I sourced a length of 3/4” ID spiral reinforced vinyl hose and found that 30” is ample. I also found a pair of 306 stainless 3/4 barb tees (later found the same in bronze) and inserted into the existing pickup hose from the old seacock to the strainer. Coupled the new seacock to the branch.

I chose Groco based on recommendations from some whose opinions I respect. I was satisfied with the prices from Defender (east coast US). The ss tee came from Amazon. They are for the commercial food and beverage industry and appeared well made. I was stuck for screw clamps as all mine were fractionally too small. They will be replaced with HPS 27-16 3/8” wide embossed clamps as the 1/2” wide ones are too wide.

The stbd engine bay has the hot water tank and hose for the shower along with some other clutter. However, I don’t foresee any major problems installing the second one in the same relative position (inboard and just ahead of the rudder post) if I deem it necessary.

An upside is that I have discovered a new contortion that allows access to the forward part of the engine 😃

I apologize for the orientation of the pics. Don’t know how to correct. Any questions please ask.
Cheers,
Rufduck

That's exactly where my generator intake is. As I mentioned, no problem with that up to now, so hopefully you have good luck as well.

[Rufduck]

Will post findings
Rufduck

[Rufduck]

Well, that was interesting…
Tested new seacock in conjunction with the original. Left dock at indicated 160*f. Both seacocks open…Engine immediately overheated. Closed saildrive seacock and used only the new one, temp dropped immediately to indicated 195*f. Ran 3.5 hours at 2500 with no change in temperature.
So, will continue to investigate different scenarios but will only use one or the other at a time.

The last time I replaced the thermostat, I never bothered to look at the open temperature. My truck diesel has two options 185*f and 195*f.
Anyone know what the open temperature for the thermostat is for VP D1-30?

Anyway, just a heads up.
Cheers, Rufduck