adding bowthruster to 60 foot ferrocement boat

[ted manos]

Originally Posted by TrentePieds

Quote: "they claimed to have no experience with Ferro cement installations."

That can hardly be characterized as "blowing you off". That seems to me to be an absolutely factual, and therefore legally unassailable statement, and one that any competent businessman would make in the circumstances, since the matter speaks to liability issues. The reply is only common sense in light of the American legal system, and the general litigiousness of American society, being what they are.

I was around - just around the corner, literally - when these FC boats were being built by Samson Marine of Richmond B.C. Some were good, some were excruciatingly bad, a fundamental problem being that the "plastering" of the "armature" has to be done in one continuous, contiguous operation so that each application of fresh, not-yet-cured aggregate reacts chemically with, and bonds with, fresh, not-yet- cured, aggregate. Nothing will bond satisfactorily to 50 year old, long since cured, aggregate. Thus cutting for a tunnel is, I will wager, a sure-fire way to ensure that the boat will sink not too long after the installation of the tunnel.

If you are interested in the ins and outs of FC boat building, I recommend that you find the little book by Jay Benford that addresses the matter in a most admirable way.

Men who earn their living on these shores handle 40 ton single screw ships as a matter of course. Such are the vessels they earn their living in. Bringing such a vessel alongside is perhaps a little frightening the first time you try it, by try it you must, and becoming competent at it is an absolute requirements for any man who would own such a ship. As someone else said: Pay for the services of a competent man to teach you how. Among the things he will tell you is that you give a pass to any mooring that is too small for your vessel - which in your case would deny you the use of finger slips in yachtsmen's marinas. Experience will teach you what is adequate and what is too small.


Here is a video of a man who knows his stuff. Single screw ship, bigger and heavier than yours. In very confined quarters. No thruster either - just competent handling:

All the best

TrentePieds

you are correct....I guess that they are not unlike the insurance people I have encountered---they don't want to get involved.

but you have given me the best advice ever about the curing.

acutually this boat hull is a 1980....but boat never in water...easy to get at now to alter but you scare me with the curing argument.

why bowthruster....well it is a big boat in a small area now with insurance issues....why risk it...when you have a technologically superior solution.

yes, a guy could luck out in a no wind condition and get into a stall but really....does one want to be terrified every time you go into port?????
and yes, I have seen sail boats use multiple techniques to control their boats but having multiple twin screws for years would want me to error on the side of safety.

so safety, bowthruster, insurance, and moving the boat to water are my conditions of taking on this project....and they are difficult to find.

thanks

[Steadman Uhlich]

Originally Posted by JOHNMARDALL

I recommend a fiberglass tube for your ferro-cement hull and also recommend an end connection method that does not require fiberglass to adhere to the concrete. If you'd like to send me a personal note, I'll give you my email address and send sketches, a step-by-step process, and a thruster recommendation. Getting the tube in the right place is the most important issue - if it's too shallow or too short, the thruster will not perform properly no matter what else you do. A very heavy 60 footer is getting to the limits of an electric thruster, so I'll also provide some information on a hydraulic unit.

Best Regards

John Mardall
Vetus Maxwell Group

John,
That's a very nice offer.

If you ever do learn of a Ferro Cement boat install, using your thrusters, please let us know the methods used to install it. Perhaps requesting some photos and description from the buyer or installer. I can imagine other buyers of big heavy FC boats would want to know how it was done.

[paulajayne]

https://www.facebook.com/media/set/?...37852272906353

[Steadman Uhlich]

Originally Posted by paulajayne

https://www.facebook.com/media/set/?...37852272906353

PAULAJAYNE,
Thanks for posting the link. It shows...

Two very good examples of cutting the thruster tunnel holes in the FC boats and the finishing.

One boat had the holes cut by a professional concrete cutting company, the other was DIY.

Do you have any info on the finishing or how the PVC pipe was attached to the hull cement? It appears that cement was used to fair the hole. Is that correct? Or was it another fairing compound? Any notes or information in the Hartley group?

[Snowpetrel]

There is a lot of good technology now to improve the secondary bonding of FC. Modern epoxies and epoxy grouts do a pretty good job.

The real key to any repairs or modifications to FC boats is to tie into the original reo and mesh. Eg if you bash the old cement back to the point where the reo and mesh is well exposed by a few inches and tie your new reo and mesh into this, then use a high strength water resistant bonding agent and a modified high strength low shrinkage repair type of cement morter the repair is likely at least as strong as the original hull.

Learning to handle a single screw long keel boat is going to be necessary anyway, thruster or not. In some ways a thruster can become an impediment to learning proper technique, and one day the thruster will fail, or the wind will be to strong for it to work well, and good old fashioned ship handling skills will be needed anyway. So if you fit a bowthruster try not to use it all the time.

On the bigger boats with no thruster we often used a dinghy with a 10 to 30 hp outboard to shunt the boat around. This worked very well with a good crew in the dink. Very effective if used properly.

Another approach is to look at your rudder. Prehaps something like an articulated rudder might work for you. And some boats fit stern thrusters into the rudder. This may be a much cheaper (though less effective) option.

[TrentePieds]

@ #16

Ted: I meant to scare you ;-0) Not because I wish you ill, obviously - quite the contrary!

Ferro is touchy stuff, and the chemical issues are not the only ones you have to contend with. The armature on most Samson boats was garden variety chicken wire laid over "pencil rod" - a skinny kinda rebar without the serrations - laid longitudinally on two inch centres on web frames formed from pencil rod. The total thickness was intended (and reputed) to be 1" (one inch), or just over, but since all steel has to be totally embedded, most hulls were of necessity thicker than that, and therefore rather over design-weight.

Jay Benford had a superior technology which is why his designs turned out to be superior to the Samson built Cece Norris designs and I have a hunch that some Samson boats built after Samson buggered off to New Zealand - I think it was - may have employed the Benford method. Benford used a building material called "weldmesh" in place of the chicken wire, and it was, in consequence of the "springiness" of the weldmesh, possible to lay up a fairer armature and therefore get a thinner, fairer hull. The Samson-built hulls often had to be faired with gobs of micro-balloons set in gallon after gallon of epoxy resin.

All that to point out that to cut though a hull of either construction takes some doing. Any joint twixt hull and a thruster tube would have to be a mechanical one employing an appropriate compound on the faying surfaces, and given the general intractability of "ferro", I should think that that problem would have to be solved with quite some care.

As you say you have multi screw experience, I wouldn't let the prospect of having to maneuver in tight quarters on a single screw frighten you too much. It obviously take a different technique, but it is not difficult to make a heavy single screw boat do a pirouette on her pivot point. It's just a knack you acquire. I think you can save yourself a lot of expense and future grief if you just learn to do that.

As an aside that sort of relates: MyBeloved came to seafaring only a coupla years ago at retirement age. She can be a bit timid about going close to "hard stuff". So I've taught her the hand signals as well as the standard helming and engine commands and her sweet, polite, Canadian self, given to circumlocution, is coming to terms with the fact that the brusqueness of navy-style "orders and responses" doesn't mean that anyone is being rude or even impolite. Last season I told her off to go forward as we were ready to leave a fuel dock, and to take the con as well as handling the lines. Neither of us likes loud voices, so in silence, using hand signals, she took us away from the dock against a wind that was holding us on, while I was being the dogsbody combination steersman and chief hengineer. You shoulda seen the grin on MB's face when a woman on the dock said: "Wow - those guys have a system!"

We are just moving TP to a new marina, and for MB's sake - and my own a little bit :-) - I've snaffled a space on a long pontoon where we can come alongside port side to, because like most people, we have a right hand screw. Once she gets the hang of that, we'll start working on backing into a finger slip. And here is a clip of some RNR "snotty" (Midshipman) showing how backing-in should be done. Twin screw, admittedly, and I suspect a little more horsepower than any of us Sunday sailors are accustomed to. Mind you, if I had been the XO, the man making that death-defying leap at the end of the clip would be at the defaulters' table and so would the snotty for not having told him not to :-)!


https://ca.video.search.yahoo.com/vi...Fwx.;_ylu=X3oD


And here is wonderfully educational clip of how NOT to come alongside on the lee side of a dock :-) Study this one and it becomes apparent that the skipper – a charterer, no doubt – hasn't a clue as to why the boat is doing what it is doing. And in the end, the dock-hand who is trying to be helpful just throws up his hands and walks away.

https://www.youtube.com/watch?v=wSxBm_-UYsA

TP

[TrentePieds]

Let's try the backing-in job again :-)

https://ca.search.yahoo.com/yhs/sear..._fremkfs_16_34

[TrentePieds]

Maybe the URL is too long. When you get the Yahoo page, click on "HMS Exploit"

TP

[knockabout]

sounds like a bag of cement / couple of litres of bondcrete / the right size thick wall sewage pipe cut to the right length / build in the thruster mounting hardware / the thought of cutting holes in a perfectly good boat / Hartley NZ had a fishing boat design with bow thruster it was very shallow draft / people started making them in steel and the same with Hartley Tahitian Yachts / may be easier to sell her intact and buy one with a bow thruster already fitted / not everybody likes that particular luxury

[HankOnthewater]

As far as the 60 ft boat by Samson, 25 ton estimate is a bit light in my opinion, more likely 40-45 tons, if it is 60 ft on deck. The C-Lord as mentioned by Steadyhand, is according to the link below 53 ft, but I am sure the bowsprit will take it to 60 ft.
Samson boat plans 'C-Lord' sail boat

I agree with Snowpetrel’s comment in post # 20. One can manoeuvre such boat after learning boat handling skills, and when wanting to come in a tight marina in adverse conditions,……. maybe it is better to anchor out, and wait for the tide, wind strength or direction to be more favourable.

There is another aspect. When owning such a large boat in ferro cement, it could mean there is a limited budget, and the cost for such large boat to stay in marinas is quite high, and you may decide for that reason NOT to frequent marinas all that often, therefore the need for a bowthruster may be less of a priority.

I have sailed, repaired, modified several concrete boats, including some Sampson designs (the largest ones were c-breeze, c-strutter and c-deuce). In my experience (many/most) epoxies adhere very well to ferro cement. I have never tried, and would not try polyester resins as they shrink when curing. I am not aware of a difference in heat expansion coefficient between epoxy with glass and ferro cement. If there is, it never caused me and the repairs any problems, and as far as I know all repairs done were good for 10 plus years, and in one boat (my own) good after 20 years.

[Snowpetrel]

Hi Hank, I agree, with a boat like that, or any boat for that matter you have to pick your battles. Anchoring out is good plan. Dinghy in and plan your approach carefully, work out your abort options. Etc

On ferro, we patched a small hole in the topsides of my folks ferro boat with standard epoxy and filler many years ago. We have noticed over the years that it has very slightly cracked around the bond area. It's not really structural, doesn't leak and has never shown any sign of rust, but the paint in that area does show occasional cracks around the bond area. This one was patched in a hurry in less than ideal circumstances and has no glassfibre reinforcing. But it has held up fine now for 25 years or so.

Other small repairs using better bonding agents and epoxies have worked very well. I believe some epoxies also shrink slightly as they cure, this may be the reason the patch got the hairline cracks. As I understand it a lot of the modern epoxy or polymer modified concretes are designed not to shrink.

[captlloyd]

I would fabricate either a steel or fiberglass tube for the thruster to mount in. Think flanges. Inside and outside flanges that can be either cemented into the hull and/or bonded/ gasketed. In my opinion very doable and a nice addition. A well done FC boat is very strong.

[Snowpetrel]

^^ capt lloyd, that would be a pretty good approach given decent sized well fitting flanges, lots of sealant and bolts set well back from the edge of the FC. Especially if you could build a watertight bulkhead aft of the bowthruster space. And tie the whole tube into some internal structure to take some of the point loads off the hull.

[Puget Dan]

We installed a external Yacht Thruster on our 38' Horstman Trimaran here in the northwest and I have been really pleased with the performance. Our Trimaran is so much easier to maneuver in tight spaces. In fact I installed it myself, once our boat yard had made the precise mounting hole for me. Net cost was about $5500.

Good luck.

Yacht Thruster - External Bow and Stern Thrusters

[TrentePieds]

Snowpetrel:

I'd forgotten about Hartley's in NZ. Are they still active?

TP