Bow thruster

Hi all,

We are wanting to install a bow thruster on our 34 CHB, and I just wanted to see how anyone that has done the job themselves, cut the hole?

Is there a tool that makes this job easier, and can you rent/buy it?

Thanks!

The problem in cutting the hole is that it is not round because it is on an angle. You can make a scribe to mark out the hole with a long rod that you bend 2 (90 degree bends) in the radius of the hole size. You then drill 2 small holes the size of the rod, one on each side of the boat. Insert the rod through the 2 holes and rotate it in a circle marking the hull as it turns. Then you have the mark for cutting the hole in the hull. To transfer the spot to drill from inside the boat I use rare earth magnets, put one on the spot inside and secure it with some tape, then go outside the boat and the other magnet will easily find the magnet on the inside.

There's a pretty good DIY Video installation video out there...YouTube I believe..

I have installed a bow and stern thruster. Comodave is right about the angle creating a huge hole. After scribing I cut mine out with a power jig saw. This was fairly easy. After grinding I used epoxy and strips of construction mat for strength on the inside and biaxial tape around the hole on the outside for a leak proof seal.
Remember when the package says "professional installation only" they are challenging your manhood leaving no other option but to press on! Sort of like when you say "hold my drink and watch this".

Don

steelydon said:

Remember when the package says "professional installation only" they are challenging your manhood leaving no other option but to press on!

Don

Click to expand...

You, Sir, have no doubt been in contact with my wife!

I did it on my cold molded hull. Once I got location figured (magnets are THE ticket here), I drilled a 1/2" center hole on both sides of the hull. Then made a wood jig to hold a die grinder to a long piece of 1/2" steel bar. Die grinder was parallel to bar axis, clamped at slightly less than half the tube diameter. With rod through both holes, I ground the hull lightly scribing the soon to be holes. Die grinder would have taken forever, so once scribed I finished the job with a sawzall. Tube slid in with an accurate fit. Easy peasy.

Below is link to Side Power (bow thruster) installation manual and covers every thing you can ask,

http://www.marinewarehouse.net/images/sidepower/Tunnel_Installation_Guide.pdf

"After scribing I cut mine out with a power jig saw."

An abrasive grit saw blade does a neater job than a metal tooth blade on most any GRP.

Am I the only one coming out in a cold sweat reading this?

menzies said:

Am I the only one coming out in a cold sweat reading this?

Click to expand...

I doubt it. Tube affixing raises my curiosity more than drilling the hole. But, there are oh so many other ways to sink a boat whether it is living in a hurricane area, aging through hull or a faulty stabilizer install.

I put a stern thruster in mine last winter. Only an 8" hole below the waterline... it is certainly not as difficult as a bow thruster, but it was a piece of cake to do. Took anout 2 days to do. If I didn't have my main water tank under the deck in the bow, I would have done a bow thruster then.

The only big deal is the ultimate working with the right type of cloth and epoxy.

Mix and prepare according to directions is easy, its working the cloth overlap that can get frustrating.

I havent done a thruster tunnel but replaced several leaking exhaust flanges with glass tube. The last were the side exhasts on my 37 Silverton for the 3208 Cats. Hardest part in getting to all surfaces in confined ares, not the conceptual parts.

Once you know how/where to cut the tupe hole, the reamst is pretty straightforward except getting the glass to conform to tight corners.

menzies said:

Am I the only one coming out in a cold sweat reading this?

Click to expand...

Nope, but it's not my boat.

So...you want to save the labor cost of having a pro do it?

I like to do all the work on my boat not just to save money, but because I like working on my boat AND it is done the way I want it done. I had fun putting in my stern thruster. I would not hesitate to do a bow thruster if it were not for the water tank I would have to loose. I may still put an external pod bow thruster on. This winter I will be replacing 11 plastic portholes with S/S ports, painting the hull and replacing the AC/DC main electrical panel. i am glad they make propane heaters...

menzies said:

Am I the only one coming out in a cold sweat reading this?

Click to expand...

No, you are not. To point out one more thing too and that is that the one person who jumped up here saying he'd done it and how is Ski, who is a professional.

Twisted tree installed a bow thruster on his previous vessel, a GB as I recall. Most likely, the OP's vessel will present some challenges, well beyond cutting the hole. Access problems and structural interference are not easy to overcome on a smaller vessel.

I planned installing one,our marina mechanic said he knew someone expert at cutting the hole accurately and correctly, but he had died recently.
I think I`d be looking for your local equivalent expert, preferably alive, rather than launching into it DIY. But if you have the skills, what could possibly go wrong?

This is video segment 3 of 12....all available on YouTube.

Thanks all for the replies. I appreciate all the feedback, and will keep you posted with how it goes! We are doing it ourselves, the water tank is out, the bed is out and the hole will be cut soon.... will post pics if people are interested.

Absolutely we need photos! If we don't see photos, it never happened... have fun and good luck.

I did it.

Some photos of my jig in this thread:

http://www.trawlerforum.com/forums/showthread.php?p=227773

I used rare earth magnets, fun tack, and a laser level to measure several hundred times before I cut.

http://www.trawlerforum.com/forums/showthread.php?p=374943

More here:

http://www.trawlerforum.com/forums/showthread.php?p=223600