Cruisers Forum
 


Join CruisersForum Today

Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on Cruisers Forums. Advertise Here
 
Thread Tools Search this Thread Rate Thread Display Modes
Old 20-06-2019, 06:22   #1
Marine Service Provider

Join Date: Aug 2011
Location: St Augustine
Boat: '87 Irwin 43
Posts: 221
Fuel tank access port

Lots of crud in my ‘87 Irwin 43 fuel tank and only access is three 1/2” threaded holes under a 12” square cabin sole lift panel. Polishing fuel seems silly (putting clean fuel back in a dirty tank). I’m reluctant to disassemble the cabin interior to remove the cabin sole to cut multiple access ports into the molded fiberglass tank...
I’m considering cutting/installing one 6”-8” access port under the 12” lift panel for tank cleaning - not perfect but significantly better access than the 1/2” holes.
Any better ideas would be appreciated! Thanks
Attached Thumbnails
Click image for larger version

Name:	9182E053-2165-4F89-AAEC-05E7EB983771.jpg
Views:	42
Size:	436.9 KB
ID:	194307   Click image for larger version

Name:	AC24DA38-F7A4-4C23-921F-A1D660B51C3D.jpg
Views:	46
Size:	437.5 KB
ID:	194308  

Click image for larger version

Name:	AA3A10F2-3CB1-4D4B-B564-C5670C9BAA5B.jpg
Views:	46
Size:	409.2 KB
ID:	194309  
__________________

malyea is offline   Reply With Quote
Old 20-06-2019, 07:08   #2
Registered User
 
Bill O's Avatar

Join Date: Jul 2015
Boat: Bruce Bingham Christina 49
Posts: 808
Re: Fuel tank access port

I assume the fuel in the pan is from your fuel filter. How long did you run that filter to accumulate the crud?
Ideally you are right, adding clean out ports to clean the tank would be the best to get the most crud out, but not fun trying to rebuild the cabin sole and fiberglass cabin insert.
Could try make your own polisher w/an automotive 12V electric pump, a hard metal pick up tube to get to the bottom of the tank and a filter, then pump out your fuel into 55 gal drums (depending on your tank size). Not perfect but did this before we moved our boat a few years ago and worked well. Barely even see a blip on the vacuum gauge when motoring in really sloppy conditions. This is something simple to try to see how it works vs. cutting up your cabin sole.
Also if you are using a biocide, this is a double edge sword and can create loads of black crud in your tank.


Bill O.
__________________

__________________
Bill O.
KB3YMH
http://phoenixketch.blogspot.com/
Bill O is online now   Reply With Quote
Old 20-06-2019, 12:26   #3
Registered User
 
tkeithlu's Avatar

Join Date: Feb 2012
Location: Carrabelle, Florida
Boat: Fiberglas shattering 44' steel trawler
Posts: 1,262
Re: Fuel tank access port

Several approaches to try before you start cutting the tank in that very awkward space. Other than suctioning it with a thin "straw," consider draining it with your fuel pump and flushing it with fresh diesel, and draining again. Messy, but every thing can be filtered in the process. If you have to have better access, consider making one of the 1/2" ports into a 3/4 or 1 inch port, while sizing down to remount the pickup tube or fuel return.
__________________
Never let anything mechanical know that you are in a hurry.
tkeithlu is offline   Reply With Quote
Old 02-07-2019, 14:44   #4
Marine Service Provider

Join Date: Aug 2011
Location: St Augustine
Boat: '87 Irwin 43
Posts: 221
Re: Fuel tank access port

I’ve decided...

I’ll soon be cutting a 6”x6” access port thru the top of my 32 year old molded in fiberglass diesel fuel tank on my ‘87 Irwin 43 sailboat.

I’ll have the local machine shop fashion a 1/8” + thick aluminum cover plate (unless there’s a better material...?).

Question - how do I attach the cover plate to the tank top in a leakproof, seaworthy and shipshape manner?

What’s best ... 12 self tapping screws, glass in a “aluminum rim” tapped for machine screws, imbedded metal threaded inserts into the fiberglass to receive machine screws, drill and tap the surrounding fiberglass for course thread machine screws...or...?

Here’s a photo of the 12”x12” cabin sole opening under which I’ll be cutting the access port into the tank top.

The question is - how best to attach a cover plate to a fiberglass fuel tank?

Thanks
malyea is offline   Reply With Quote
Old 02-07-2019, 15:28   #5
Registered User
 
wingssail's Avatar

Join Date: Jan 2010
Location: On Vessel WINGS, wherever there's an ocean, currently in Mexico
Boat: Serendipity 43
Posts: 1,270
Send a message via AIM to wingssail Send a message via Skype™ to wingssail
Re: Fuel tank access port

Quote:
Originally Posted by malyea View Post
What’s best ... 12 self tapping screws, glass in a “aluminum rim” tapped for machine screws, imbedded metal threaded inserts into the fiberglass to receive machine screws, drill and tap the surrounding fiberglass for course thread machine screws...or...?
Assuming that the fiberglass is at least 5mm thick then I would use #12 (or 1/4" x 20) machine screws spaced about 25mm apart around the hole. The top of the tank where the hole is must be flat. The screw holes must be tapped with the proper sized tap. You can then use a rubber gasket and/or sealant. Be careful not to over tighten the screws which could strip the threads.
__________________
Sailing is a sport, an athletic activity, not a sedentary one.
Fred Roswold-Fred & Judy, SV Wings, Mexico
http://wingssail.blogspot.com/
wingssail is offline   Reply With Quote
Old 02-07-2019, 16:11   #6
Registered User

Join Date: Nov 2013
Location: Nice, France
Boat: Hunter Marine 38
Posts: 661
Re: Fuel tank access port

When I installed an inspection hatch in my fuel tank I inserted bolts in the pre drilled holes, from inside the tank to outside. The end of the threaded bolt was flattened on 2 opposing sides, enabling me to put a nut on the bolt and tighten the nut while holding the bolt with a big plier. It works, you just need 2 hands.
sailormed is offline   Reply With Quote
Old 02-07-2019, 16:16   #7
Marine Service Provider

Join Date: Aug 2011
Location: St Augustine
Boat: '87 Irwin 43
Posts: 221
Re: Fuel tank access port

Quote:
Originally Posted by wingssail View Post
Assuming that the fiberglass is at least 5mm thick then I would use #12 (or 1/4" x 20) machine screws spaced about 25mm apart around the hole. The top of the tank where the hole is must be flat. The screw holes must be tapped with the proper sized tap. You can then use a rubber gasket and/or sealant. Be careful not to over tighten the screws which could strip the threads.
Drill and tap directly into the fiberglass?
malyea is offline   Reply With Quote
Old 02-07-2019, 17:22   #8
Registered User

Join Date: Jul 2014
Posts: 159
Re: Fuel tank access port

You can make a fiberglass (epoxy?) ring the has an ID = the OD of the hole. OD of the ring = a hair bigger than OD of the metal plate. Make sure the top of the ring is perfectly flat (plate/gasket will seal to the top of this ring), glass that ring to the top of the tank with epoxy putty. Make sure you use enough epoxy putty to seal around the ring/tank interface to prevent leaks.

Now tap into the epoxy ring and install your metal plate with gasket. If you make ring about 3/8" thick, that would give you enough thread depth to tap and you won't penetrate the tank with the bolts (potential leaks).
scherzoja is offline   Reply With Quote
Old 02-07-2019, 17:25   #9
Senior Cruiser
 
mabowers's Avatar

Cruisers Forum Supporter

Join Date: Feb 2018
Location: In the air or on the water
Boat: Southern Cross 39
Posts: 109
Images: 14
Re: Fuel tank access port

I am considering something similar. There was an existing soft patch on top of my 50 gal fuel tank. I just had a mechanic pull it, to power wash, solvent rinse, & dry my tank, after I plugged 2 Racors during a storm 6 miles off Sarasota FL a couple weeks ago. I could not believe the sludge & slime we pulled out.

Leaning toward replacing the soft patch with a G-10 plate and cover, with some threaded inserts to hold the (gasketed) cover on rather than trust the existing tapped holes in the fiberglass tank top.




mabowers is online now   Reply With Quote
Old 02-07-2019, 19:50   #10
Registered User
 
gamayun's Avatar

Join Date: Aug 2013
Location: Oakland, CA
Boat: Freedom 38
Posts: 2,016
Re: Fuel tank access port

Following! I'm having to do the same soon (but with an aluminum tank) so any discussion about fuel polishing and access ports kinda perks me up
gamayun is offline   Reply With Quote
Old 07-07-2019, 13:12   #11
Marine Service Provider

Join Date: Aug 2011
Location: St Augustine
Boat: '87 Irwin 43
Posts: 221
Re: Fuel tank access port

Quote:
Originally Posted by sailormed View Post
When I installed an inspection hatch in my fuel tank I inserted bolts in the pre drilled holes, from inside the tank to outside. The end of the threaded bolt was flattened on 2 opposing sides, enabling me to put a nut on the bolt and tighten the nut while holding the bolt with a big plier. It works, you just need 2 hands.
Interesting...let’s say I’m using twelve bolts, all sticking up out of the tank from inside to outside - how do I get all twelve bolts to stay in place while I lower the cover plate in place to then add a washer/nut to each of the bolts? Thanks
malyea is offline   Reply With Quote
Old 07-07-2019, 13:22   #12
Marine Service Provider

Join Date: Aug 2011
Location: St Augustine
Boat: '87 Irwin 43
Posts: 221
Re: Fuel tank access port

Quote:
Originally Posted by scherzoja View Post
You can make a fiberglass (epoxy?) ring the has an ID = the OD of the hole. OD of the ring = a hair bigger than OD of the metal plate. Make sure the top of the ring is perfectly flat (plate/gasket will seal to the top of this ring), glass that ring to the top of the tank with epoxy putty. Make sure you use enough epoxy putty to seal around the ring/tank interface to prevent leaks.

Now tap into the epoxy ring and install your metal plate with gasket. If you make ring about 3/8" thick, that would give you enough thread depth to tap and you won't penetrate the tank with the bolts (potential leaks).
I think your main point/advantage is to avoid drilling thru tank top in order to negate the risk of leakage - correct.

I’d like to gain a higher level of confidence in “drilling and tapping” threads directly into either fiberglass or cured epoxy - have you (who has...) actually drilled and tapped threads into fiberglass and/or epoxy? (Obviously I haven’t - have only drilled and tapped aluminum).

Thanks
malyea is offline   Reply With Quote
Old 07-07-2019, 13:26   #13
Marine Service Provider

Join Date: Aug 2011
Location: St Augustine
Boat: '87 Irwin 43
Posts: 221
Re: Fuel tank access port

Quote:
Originally Posted by mabowers View Post
I am considering something similar....

Leaning toward replacing the soft patch with a G-10 plate and cover, with some threaded inserts to hold the (gasketed) cover on rather than trust the existing tapped holes in the fiberglass tank top.
What type of “threaded inserts” are you considering? I’ve also thought of something similar. Thanks
malyea is offline   Reply With Quote
Old 07-07-2019, 13:40   #14
Registered User

Join Date: Dec 2012
Posts: 16
Re: Fuel tank access port

Take a look at this site. They have an interesting tank access "answer":
http://www.seabuilt.com/
FL Dan is offline   Reply With Quote
Old 07-07-2019, 20:55   #15
Registered User

Join Date: Jul 2014
Posts: 159
Re: Fuel tank access port

Malyea,

I have tapped both epoxy and fiberglass. Polyester-based fiberglass matrix does not tap well or hold machine screws well. I did this as a test and will never tap into poly-based fiberglass (other than temporary holding of something). I will and have tapped epoxy, both straight epoxy and mixed with powered glass filler. I don't trust it for heavy loads like grab rails, cleats, or winches (those get through bolts), but I will use tapped epoxy for things like securing deck fills, the storm hood over the companionway hatch, securing deck hatches (as long as there is a 'breakwater/dam" around the hatch to deflect green water), water tank lids under settees, and interior shelf cleats where there is a possibility of moisture causing wood cleats to rot.

Water Tanks - New Custom Access Ports - LA Gallery
My water tank lids are slightly different for your project in that the epoxy 'ring' is on the inside and they are blocks, not a continuous ring.


Epoxy is better for tapping and holding the screws. Somewhere on this forum, Thin Water posted posted a thread discussing whether epoxy with no filler or epoxy with filler (and what type of filler) is stronger for holding machine screws.

For your application, making a ring of epoxy (or better, buy G10, https://www.mcmaster.com/g-10) might be a good solution. G10 will have a perfectly flat top surface for the gasket to seal and when you use epoxy putty to adhere this G10 ring to the tank top, you will not have to worry about making the top of the tank perfectly flat/smooth. You also will not have any bolts penetrating the tank.

I agree with another poster that you should use a round hole, not a square hole (cut with a 6" or 8" hole saw).


Quote:
Originally Posted by malyea View Post
I think your main point/advantage is to avoid drilling thru tank top in order to negate the risk of leakage - correct.

I’d like to gain a higher level of confidence in “drilling and tapping” threads directly into either fiberglass or cured epoxy - have you (who has...) actually drilled and tapped threads into fiberglass and/or epoxy? (Obviously I haven’t - have only drilled and tapped aluminum).

Thanks
__________________

scherzoja is offline   Reply With Quote
Reply

Tags
fuel, fuel tank

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Diesel Fuel Tank Inspection Port Briarpatch Construction, Maintenance & Refit 2 06-03-2017 23:22
440: Water Tank Access Port cll2 Lagoon Catamarans 3 21-04-2015 10:20
Inspection port on fuel tank magique Engines and Propulsion Systems 5 16-01-2014 07:34
What Sealant for Inspection Port on Fuel Tank? SV Demeter Construction, Maintenance & Refit 10 23-12-2012 10:22
For Sale: SeaBuilt Fuel Tank Access CampDavid Classifieds Archive 2 14-11-2010 07:12

Advertise Here


Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 09:27.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
×

ShowCase vBulletin Plugins by Drive Thru Online, Inc.