Jump to content

Welcome to TheMalibuCrew!

As a guest, you are welcome to poke around and view the majority of the content that we have to offer, but in order to post, search, contact members, and get full use out of the website you will need to Register for an Account. It's free and it's easy, so don't hesitate to join the TheMalibuCrew Family today!

Drilling into gelcoat for thru-hull intake fitting


Fman

Recommended Posts

Does anyone have a video or you tube link on how to properly drill into gelcoat? I am going to be adding (2) 1" thru hull fittings in the bottom bilge area of the boat. From what I have been told, you should start in reverse until the gelcoat is etched and you are into the fiberglass. A bi-metal blade works best, with a hole-saw style type of bit with a guided center bit.

Anyone here have any personal experience doing this? I have contacted wakemakers and they said it is not that difficult to do, just a little nerve racking drilling a hole in your boat.

I will be doing this project to add seperate 750 fly hi's to the rear ski lockers with JABSCO pumps. The Jabsco pumps drain and filll from the same intake, and require 1" thru hulls instead of 3/4" which Malibu uses.

Thanks for any feedback.

Link to comment

Does anyone have a video or you tube link on how to properly drill into gelcoat? I am going to be adding (2) 1" thru hull fittings in the bottom bilge area of the boat. From what I have been told, you should start in reverse until the gelcoat is etched and you are into the fiberglass. A bi-metal blade works best, with a hole-saw style type of bit with a guided center bit.

Anyone here have any personal experience doing this? I have contacted wakemakers and they said it is not that difficult to do, just a little nerve racking drilling a hole in your boat.

I will be doing this project to add seperate 750 fly hi's to the rear ski lockers with JABSCO pumps. The Jabsco pumps drain and filll from the same intake, and require 1" thru hulls instead of 3/4" which Malibu uses.

Thanks for any feedback.

If you google it I'm sure there will be some great instructions, I know it has something to do with drilling in reverse, But I'm with you on drilling anything into my boat
Link to comment

Just drilled in my underwater lights, the hole was 5/8 with two smaller holes on the sides... Start in reverse untill you get through the gel, then flick it into forwards. Drill from the outside of the boat in, and use a good sealant. You will be right..

Or, tap into the factory bilge drain holes and don't drill any holes.

Link to comment

Just drilled in my underwater lights, the hole was 5/8 with two smaller holes on the sides... Start in reverse untill you get through the gel, then flick it into forwards. Drill from the outside of the boat in, and use a good sealant. You will be right..

Or, tap into the factory bilge drain holes and don't drill any holes.

Plus1.gif That's what I have done in the past. Works like a champ.

Link to comment

Just drilled in my underwater lights, the hole was 5/8 with two smaller holes on the sides... Start in reverse untill you get through the gel, then flick it into forwards. Drill from the outside of the boat in, and use a good sealant. You will be right..

Or, tap into the factory bilge drain holes and don't drill any holes.

sorry for the slight hijack, but do those underwater led's attract any fish when parked in the harbour like that?

Link to comment

I'd ask to see if the factory would do it for you (congrats on the new boat btw, you will not be disappointed). I'm planing on doing the same this spring. Not hard at all to drill holes in gelcoat, use masking tape and drill slowly in reverse, sand the edge smooth afterwards. Here is an interesting link I've saved from ww:

http://www.wakeworld.com/forum/showthread.php?t=784486

Link to comment

I'd ask to see if the factory would do it for you (congrats on the new boat btw, you will not be disappointed). I'm planing on doing the same this spring. Not hard at all to drill holes in gelcoat, use masking tape and drill slowly in reverse, sand the edge smooth afterwards. Here is an interesting link I've saved from ww:

http://www.wakeworld.com/forum/showthread.php?t=784486

That article has good advice. I would also measure from a known point that you can locate on both the inside and outside of the boat (like an existing through hull) you don't want to be putting that in the wrong place, like on top of a trailer bunk. I was thinking throught pro's and con's of drilling a pilot hole from the inside - as long as you had a good idea of where that would be located on the outside.

Pro -That would allow you to put it exactly where you want it on the inside.

Con- make sure the approximate location on the outside is flat, free and clear.

Link to comment

Thanks for all the advice, I was told to start a small pilot hole from inside the boat to make sure you are in the correct spot. It will chip the gelcoat a little but with the larger hole it is no problem. I thought about using the intake with the drain handle, but unfortunately it is 3/4" and the JABSCO pumps require a 1" hole to perform correctly. Will definitely use some masking tape witrh a brand new bit, and bi-metal holesaw blade. I am going to do the intakes down near the transmission area, and mount the JABSCO pumps on the rear panel above the transmission. This where wakemakers is doing it and they fit with no problems with easy access if you ever need to replace an impeller.

I am setting up the system to have a fill/drain toggle for each bag, they are going to be used for surfing. My kids are all over the wakeboarding, but my low back is beginning to not like the torque of wakeboarding. I wanted the bags to be completely seperate from the stock Malibu ballast system.

I installed a ballast system on my Supra and used the Tsunami 800's, but they never could get all the water out of the bags without lifting them up. The JABSCO pumps have great reviews for draining because they will prime themselves and suck the water out of the bag. You also dont need a vented loop, or second pump with the JABSCOs becausr they are reversible. I am considering the timer for an extra $100 to automatically shut-off once the bag is empty.

The only problem I can see is where to mount the toggle switches. The '11 VLX dash is so clean it would be a bummer to add toggles in the dash. I might just mount them below the dashline in some of the plastic tabs I saw that Bakers Marine is selling. Has anyone else here mounted the switches in a different location?

Edited by Fman
Link to comment

I'd ask to see if the factory would do it for you (congrats on the new boat btw, you will not be disappointed). I'm planing on doing the same this spring. Not hard at all to drill holes in gelcoat, use masking tape and drill slowly in reverse, sand the edge smooth afterwards. Here is an interesting link I've saved from ww:

http://www.wakeworld.com/forum/showthread.php?t=784486

Unfortunately Malibu will not do this, and they only use 3/4" intakes for the Phiranha pumps, the JABSCO's need 1".... Malibu wont even install speakers in certain locations, I am getting two inboat speakers in boxes because they dont want to do the bow speakers unless I purchase a different soundpack from them. The dealer is a little disappointed with them, but thats how they streamline the installs. Not a big deal really....

Link to comment

Most people hit on the right stuff - Put masking tape down on where you want to drill, drill from outside in, start with a small pilot hole in Reverse first:) Hole saw will work but be careful! and make sure to countersink:)

Link to comment

Most people hit on the right stuff - Put masking tape down on where you want to drill, drill from outside in, start with a small pilot hole in Reverse first:) Hole saw will work but be careful! and make sure to countersink:)

What other blade would you recommend other than a holesaw blade? I cant think of anything else that would work for a 1" hole.

Link to comment
  • 3 weeks later...

I'd ask to see if the factory would do it for you (congrats on the new boat btw, you will not be disappointed). I'm planing on doing the same this spring. Not hard at all to drill holes in gelcoat, use masking tape and drill slowly in reverse, sand the edge smooth afterwards. Here is an interesting link I've saved from ww:

http://www.wakeworld.com/forum/showthread.php?t=784486

I've been looking at this more after reading how Big Jay and Cdoogles installed their pumps:

I'm leaning towards installing a separate intake for each additional pump. The ww thread has me somewhat worried about delamination. Section 7.2.2 in the manual bellow applies (I think) to the way malibu installs the ballast water intakes:

http://www.westsystem.com/ss/assets/HowTo-Publications/Fiberglass-Boat-Repair-and-Maintenance.pdf

Edited by Dexter
Link to comment

Yep drill a tiny pilot hole from the inside out first...

On your bi-metal holesaw blade, get one that has the smaller regular drill bit in the center of it, it keeps it centered and from skipping sround...Lowes, HD all have those, and get a FINE toothed blade for metals vs a ROUGHT CUT blade for woods, those are for routing wire bindles thru 2x4's for inwall construction quickly, VERY ROUGH CUT...as many tiny little teeth as possible, this is what is going to keep your gell from chipping....wear safety glasses as that dust will fall straight into your eyes and dont breath in that fibergalss/gel coat dust falling in your face... and when the 1" blade starts contact with the gel, very very little pressure, go real slow and let the teeth of the blade just barely scrape away the gel coat slowly... ensure the spot you pick is as flat as possible for a good seal.

Link to comment
  • 4 weeks later...

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...