Hendo's Randall 35 Cray Boat complete rebuild, Perth, Western Australia

[Art]

Greetings,
Mr. H. I second hinge to the top. Buy a cheap book. If you forget to dog your port when leaving the boat, it could fall completely open if hinged at the bottom. If hinged at the top, would probably only open a crack...Think hard, driving rain time.

And... The ports on most boats have either built in friction hinge or capability to tighten hinge bolts for friction that will support weight of the porthole glass frame. That way the open volume area can be adjusted to nearly any scope. Some times on chilly days/nights only a 1/2 inch crack is sufficient.... some times half way or wide open is appreciated.

 

[Insequent]

Hinge at the top is normal. But feel free to be weird!

 

[Hendo78]

Greetings,
Mr. H. I second hinge to the top. Buy a cheap book. If you forget to dog your port when leaving the boat, it could fall completely open if hinged at the bottom. If hinged at the top, would probably only open a crack...Think hard, driving rain time.

Thank you Mr RTF


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[Hendo78]

And... The ports on most boats have either built in friction hinge or capability to tighten hinge bolts for friction that will support weight of the porthole glass frame. That way the open volume area can be adjusted to nearly any scope. Some times on chilly days/nights only a 1/2 inch crack is sufficient.... some times half way or wide open is appreciated.

Thanks mate! Good points


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[Hendo78]

Hinge at the top is normal. But feel free to be weird!

Haha


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[Hendo78]

Today I did a bit of sanding on the rubbing rail strake as well as on the lower rub rail and rail fillets. Couple of little patches done today that need to be sanded up tomorrow then the epoxy barrier cost can be applied to the fillets and lower rub rail. I started Sanding the filler I applied on Friday arvo but it is still too soft so I have to skip that section for a few more days (possibly a week depending on temps). Not like I'm pressed for things to do on her tho eh so no big deal. Back in to it tomorrow.






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[CPseudonym]

The beer holder is looking great mate!

 

[Hendo78]

The beer holder is looking great mate!

Lol thanks Craigo. Will be great when I'm swimming and become parched and in need of a refreshment lol


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[Art]

Matt - What I say here may be thought of as cruel...


If you made rule that no beers until first splash - you'd be finished faster than a wink!! - LOL


What you're doing always looks good!

 

[Hendo78]

Matt - What I say here may be thought of as cruel...


If you made rule that no beers until first splash - you'd be finished faster than a wink!! - LOL


What you're doing always looks good!

Hahahaha no chance brother..!


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[Hendo78]

I'm looking at bilge ventilation as well as fresh air intakes for the engine and there are some ugly vents so i went googling and found these. What's your thoughts? What do y'all have? Would love to see some pics and ideas.

Thanks in advance guys






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[CPseudonym]

I like that design Matt but have you calculated the vent size needed yet?

http://www.proboat.com/2015/06/venting-the-engineroom/

 

[Art]

Nice looking - Remember, more free air is better than less under most circumstances.

 

[Insequent]

Good ER ventilation is critically important. Definitely calc what you need by way of the article Craig referenced or some other means. Best to overdo it to help with heat in ER also. Poor ER ventilation is surprisingly common and can cause premature engine failure.

I have some Vetus vents, not cheap unfortunately.
Louvered Engine Room Air Vent - Vetus Denouden | Fisheries Supply
We made a dorade system for them because we lacked the depth in the hull to use the Vetus ones.

I'm using 2 x 750 cfm Delta T axial vans for the air intakes (4 intake vents all up, two on outside the hull and two on inside to walkaround deck) at the front of the ER. Then at the rear of the ER I have 2 x 350 cfm centrifugal fans ducted to the two rear ER vents for outlet.

Apart from volume, stopping rain and big waves is also a must. For the rain and spray the dorade style design in post #1 is good. But for prevention of downflooding in a roll in big seas you would ideally have air intake as high as possible and avoid the hull sides where the ER is situated. If you are able to do it, ventilation via ducts from vents high in the superstructure is ideal.

It was rain entering my ER vents that caused my black steel fuel tanks to fail, although it did take 30 years for them to start leaking.

 

[Art]

I like that design Matt but have you calculated the vent size needed yet?

Venting the Engineroom - Professional BoatBuilder Magazine

Good link, Craig - Thanks!

 

[THD]

Matt:

On the ports, if hinges on top-I have seen older ones where there was a chain with a "T" at the end hanging down, when the port was opened the "T" fit in one of the dogs to hold it open. The length of the chain could be easily adjusted depending on how open you want it to be. Cheap, effective solution.

 

[Hendo78]

Sanding fillets today. I went below and had lunch in the bilge to admire an area that is completed lol (sometimes ya get motivation from the strangest places). I then cut out engine and bilge air intakes. Still need to make dorade boxes for it but they look good so far I reckon. I epoxy coated the fillets and cut outs. Last pic is cross section from the intake cut out showing layering (20mm ply, coat of epoxy, fibreglass, 5mm glue/fillet, sanding filler, jotafair, 3M filler, epoxy barrier coat)















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[Hendo78]

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[Hendo78]

I like that design Matt but have you calculated the vent size needed yet?

http://www.proboat.com/2015/06/venting-the-engineroom/

Thanks for the link mate. Didn't realise there was a formula. I did the calc and came up with 240. Not sure what that means lol so made my vents big lol.

Thanks again mate.


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[Hendo78]

Nice looking - Remember, more free air is better than less under most circumstances.

Roger that


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[Hendo78]

Good ER ventilation is critically important. Definitely calc what you need by way of the article Craig referenced or some other means. Best to overdo it to help with heat in ER also. Poor ER ventilation is surprisingly common and can cause premature engine failure.

I have some Vetus vents, not cheap unfortunately.
Louvered Engine Room Air Vent - Vetus Denouden | Fisheries Supply
We made a dorade system for them because we lacked the depth in the hull to use the Vetus ones.

I'm using 2 x 750 cfm Delta T axial vans for the air intakes (4 intake vents all up, two on outside the hull and two on inside to walkaround deck) at the front of the ER. Then at the rear of the ER I have 2 x 350 cfm centrifugal fans ducted to the two rear ER vents for outlet.

Apart from volume, stopping rain and big waves is also a must. For the rain and spray the dorade style design in post #1 is good. But for prevention of downflooding in a roll in big seas you would ideally have air intake as high as possible and avoid the hull sides where the ER is situated. If you are able to do it, ventilation via ducts from vents high in the superstructure is ideal.

It was rain entering my ER vents that caused my black steel fuel tanks to fail, although it did take 30 years for them to start leaking.

Thanks for the post and link mate. How did you make the dorade boxes? Don't suppose you have any pics do you?


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[Hendo78]

Matt:



On the ports, if hinges on top-I have seen older ones where there was a chain with a "T" at the end hanging down, when the port was opened the "T" fit in one of the dogs to hold it open. The length of the chain could be easily adjusted depending on how open you want it to be. Cheap, effective solution.

Thanks THD. Good idea mate. Might have to look at something similar


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[bfloyd4445]

I'm looking at bilge ventilation as well as fresh air intakes for the engine and there are some ugly vents so i went googling and found these. What's your thoughts? What do y'all have? Would love to see some pics and ideas.

Thanks in advance guys




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To be honest it scares me. That large of an opening that close to the sea looks like an invitation for disaster. Needs to be designed to close if under water. That tiny little drain hole isn't likely to stop water over flowing into your bilge. Nordhavn has the best system and also uses a dry exhaust I believe

 

[RT Firefly]

Greetings,
Mr. H. I tend to agree with Mr. bf. That big an opening just, what appears to be .5 m or so, above the water line is, IMO, an invitation for disaster UNLESS you can guarantee a fail safe, positive closure if broadsided by the sea.

Maybe make the outboard deflector baffle higher??? Much larger drain???

 

[Art]

Don't mean to be a naysayer Matt. Knowing how two steps forward and three steps back can impinge upon the energy and ego of a true creator... such as yourself. But, I too am not in favor of pictured positioning for ER vent holes. Think carefully on what alternatives you may have. Maybe you do know of vent louver system that closes completely when broadside wave hits... or... maybe you have way to divert incoming water and rout it immediately back overboard. If there is one thing I've gotten to know about you... is that you'll figure out this puzzle too!

 

[Hendo78]

To be honest it scares me. That large of an opening that close to the sea looks like an invitation for disaster. Needs to be designed to close if under water. That tiny little drain hole isn't likely to stop water over flowing into your bilge. Nordhavn has the best system and also uses a dry exhaust I believe

What drain hole? I haven't added any holes yet. Are you referring to the screw hole?


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[Insequent]

Thanks for the post and link mate. How did you make the dorade boxes? Don't suppose you have any pics do you?


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Can't find any pics of my pseudo-dorade set-up, but I'll try and describe them. A pic of the transom show part of a hause hole. This indicates the width of the cavity between the external hull and the inside wall of the cockpit, a bit under 2" at a guess. As I have walkaround side decks I have the same size cavity along the sides of the boat, and the vents are cut into that cavity. Originally vents were just into the external hull. But I put vents on the inside as well, and this double-sided vent config enabled us reasonable access to put in a floor in the cavity below vent level, with some raised ends. An external drain clears any trapped water.

The original vents had vertical louvres, good for avoiding spray intake while moving forward. But they were very susceptible to rain ingress when at the dock, which is what led to the fuel tanks rusting. The new horizontal louvres might be at risk of spray underway, but there are spray/rub rails below the vents that provide some protection. Rain ingress is no longer going to happen. I have covers for the vents so if I think I'm going to get a lot of spray or water up the sides and into the external vents I can cover them up but still get air intake from the vents in walkaround deck well, which are larger in area than the original vents anyway.

Hope this description makes sense.....

 

[Hendo78]

Greetings,
Mr. H. I tend to agree with Mr. bf. That big an opening just, what appears to be .5 m or so, above the water line is, IMO, an invitation for disaster UNLESS you can guarantee a fail safe, positive closure if broadsided by the sea.

Maybe make the outboard deflector baffle higher??? Much larger drain???

Again this is just the hull cut out. No dorade boxes or drain holes have been made yet.


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[Hendo78]

Don't mean to be a naysayer Matt. Knowing how two steps forward and three steps back can impinge upon the energy and ego of a true creator... such as yourself. But, I too am not in favor of pictured positioning for ER vent holes. Think carefully on what alternatives you may have. Maybe you do know of vent louver system that closes completely when broadside wave hits... or... maybe you have way to divert incoming water and rout it immediately back overboard. If there is one thing I've gotten to know about you... is that you'll figure out this puzzle too!

Then stop being one haha. All good mate. I appreciate your support both positive and not so positive. The cutouts are at the top of the engine room. That's the highest they can go. I'll take into account the words of advice and cautions noted here.


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[Hendo78]

Can't find any pics of my pseudo-dorade set-up, but I'll try and describe them. A pic of the transom show part of a hause hole. This indicates the width of the cavity between the external hull and the inside wall of the cockpit, a bit under 2" at a guess. As I have walkaround side decks I have the same size cavity along the sides of the boat, and the vents are cut into that cavity. Originally vents were just into the external hull. But I put vents on the inside as well, and this double-sided vent config enabled us reasonable access to put in a floor in the cavity below vent level, with some raised ends. An external drain clears any trapped water.

The original vents had vertical louvres, good for avoiding spray intake while moving forward. But they were very susceptible to rain ingress when at the dock, which is what led to the fuel tanks rusting. The new horizontal louvres might be at risk of spray underway, but there are spray/rub rails below the vents that provide some protection. Rain ingress is no longer going to happen. I have covers for the vents so if I think I'm going to get a lot of spray or water up the sides and into the external vents I can cover them up but still get air intake from the vents in walkaround deck well, which are larger in area than the original vents anyway.

Hope this description makes sense.....

Ah ok cool cool. Thanks mate


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