HARBOUR INQUIRY

Hawke's Bay Tribune, Volume XVII, 30 August 1927, Page 5

HARBOUR INQUIRY

TO-DAY’S PROCEEDINGS MASTER MARINER'S EVIDENCE. FOUND NO DIFFICULTY IN WORKING INNER HARBOUR.

The Napier Harbour Commission resumed its sitting at Napier this morning, Mr. J. S. Barton, S.M.. of Wanganui, presiding. Associated with him were Messrs. A. C. McKenzie, harbour engineer, of Mel bourne, and J. B. Waters, merchant, of Dunedin

Mr. A. Gray, K.C., of Wellington, with Mr. M. R. Grant, of Napier, appeared for the Napier Harbour Board, while Mr. H. B. Lusk, of Napier, represented the Marine Department. William Robert Allan, master mariner and shore-master for Richardson and Co., said he had been in command of 'various vessels trading to the different ports. He ». s formerly a pilot in the Fiji group. He had traded in and out of Napier for over 12 years, during which period he visited chiefly the Inner Harbour. He had rarely experienced any difficulty in working the Inner Harbour and then under the worst of conditions, such as a strong flood tide and a westerly gale. Generally speaking there ' was rarely much easterly weather at Napier. The prevailing winds would be a right a-beam when entering while a south-easterly would be on the forequarter. There was very little time lost in working vessels in the Inner Harbour and lightering in the roadstead. During the eight months of this year not more than six or seven days had been lost. The maxixmum velocity of the current between the moles was five to six knots. Most of the smaller vessels went in against that current. Of the larger ones some might come in but others might wait for slack water. There was a period of an hour on either side of slack water during which there was very little tide. It would take at least a 7ft. wave to prevent lighters from working in the roadstead. During an easterly there might be 4ft. waves at the entrance to the moles, but it would not interfere with navigation. When approaching the Inner Harbour during easterly weather the seas would vary to north-east in the moles.

THERE IS ONLY ONE HARBOUR

Captain Allan stated that he had been to the Breakwater when the range had been considerable, even with a moderate blow. When there was a heavy range at the Breakwater it would be somewhat similar near the Inner Harbour entrance, but would in no way interfere with navi Ktion. In the proposed Inner Harur outer channel, Captain _ Allan considered that it would be quite safe to work any class of vessel in a current up to three knots. Mr. Lusk. You share your manager’s opinion that the Inner Harbour is essential for your fleet"—Yes. There is only one harbour. You don’t agree with what a number of navigators have said?— No, not with all of them. Is it a fact that the prevailing winds are westerly, and strong at that?—That is so, but they don't interfere with the navigation of the port When lightering vessels in the bay, isn’t there a number of days when only one side of the vessel could be worked?—Only a very few About the current, you rely upon the naval almanac?—No, not necessarily. But surely you would rely upon it? —As a stranger, but not necessarily when knowing a port. Large vessels drawing 26 feet and 500 feet in length would have to wait for slack water?—Not necessarily. There would be a period before and after alack water when they could be taken in. Supposing it was a vessel drawing 24 feet, when would you take that In?—Up to a three-knot current. Do you agree that it would be essentia] to have a tug at the Inner Harbour?—Yes. at either harnour. You are aware that the harbourmaster has for years worked large vessels at the Breakwater despite being in its uncompleted state?— Yes.

Doesn't that alter your opinion?— no. You will agree that the harbourmaster can give a better opinion than you regarding the range at the Breakwater?—No, I am just as able to form an opinion as he is. Mr. Gray: During certain bad weather conditions both harbours would have their difficulties?—Yes. but not so much at the Inner Harbour. WORKED HARBOUR AT NIGHT You have worked the Inner Harbour at night and during all stages of the tide?—Yes. You say that the current does not exceed six knots?—Yes. Supposing that the outer channel was dredged to 34 feet at low water slack a vessel drawing 26 feet would have ten feet under her keel

If a new wharf was built at he Breakwater pointing to the entrance would not a vessel going out during an easterly have the sea on her beam ?—Yes.

And there would be a certain amount of risk of the vessel being blown somewhat off her course?— Yes. Mr Lusk: But the vessel would oe outside before she caught the sea on her beam?—Yes.

And there is plenty of water there P Yes. bnt not deep water. Mr. Barton: Supposing a channel is made 600 feet wide, what margin could you allow for siltation before starting maintenance dredging?— Five hundred feet would be the margin of safety. Assuming that you had a lighter that could not be worked in a lift exceeding two feet, how many days during the year would you expect to be able to work such a vessel ?— About 200 days. Mr. McKendie: What size vessels do you keep back for slack water?— Four hundred-ton boats, but they cap be worked at any time during the flood tide, * Mr. Waters: Could you work a vessel in the roadstead as quickly as at a wharf with every facilities?— No but »t the present time loading in the bay is about 50 per cent, qnicker. MR D. HOLMES CROSSEXAMINED. At this stage, Mr. Dudley Holmes, harbour engineer, was recalled, Mr Barton asked Mr. Holmes if

he thought that a launch tug at either harbour was necessary?— Boats are handled successfully at Nelson and Timaru without, and I think that they could do it here. You have not included in your estimates anything for the protection of the foreshore?—No, that is outside the harbour works. You have made no allowance for the protection of the low-lying lands of Meeanee and Greenmeadows?— That was outside harbour consideration.

Would there be times when the outer channel could be dredged when construction on the Breakwater could not be proceeded with —Yes. How would the working of the Kaione compare with the working of the Whakariri out there?—A bucket dredge was most unsuitable, while the Kaione could be fitted with a special head that would allow her to be worked during a 4ft. lift. The shallower the water the greater the range she could work in.

If the dredgemaster in Wellington made a statement that it would De risky to work on more than a three feet lift, do you agree with him?— That all depends on the type of dredge. If he made that statement in selation to the Kaione. would vou agree?—Yes, if working with a fixed head, but not if working with a swivel head. What would you consider to be a margin of safety in regard to the proposed outer channel?—About foui feet of a lift.

Do you agree with Mr R W. Holmes that once the channel was dredged maintenance dredging would be necessary for three years?—l would not like to give you an opinion. as there might be a number of unknown factors. Seeing that there might be unknown factors, what margin of safety would vou recommend should be taken?—l believe that once the channel was dredged, and with the assistance of the propellers, that it would tend to scour and deepen, involving but little maintenance. 1 don’t think there would be much risk of much silting during the next three years. A. certain amount of risks often had to be taken in various work. I think that Cullen and Keele’s remarks that the interesting theory of the sand drift must be given up being applied here. The erosion as shown bv the soundings has been very slow, and if the material is passed into the channel at the rate suggested I believe that rhe ebb current would keep the channel clear. I would suggest that the Commission should go out on the J.D.O. and test the bottom Although the gre’- wache silt was firm it was easily cut by a cutter dredge and handled economically.

Having given up the sand drift theory, do you know of any other natural forces which might raise a doubt as to the channel being kept clear for three years without dredg ing."—There is nothing else. The silt from the Tutaekuri is inclined to go to the westward. Would the scouring action that vou would expect tend to cut down ihe sides and deposit it in the channel? — That might happen but whqthjr it would stay there would be a different matter.

Would it stay there?—There mignt be a possibility. Would the tide and easterly seas have their mark on the channel? — In time I would expect the bottom from the Breakawater to the channel to become eroded. Would not such erosion tend to obiliterate the channel as a channel? —Not with the other forces that are acting there. If similar forces were not acting in Patea after a six days' blow the channel viwuld be filled up Do vpu suggest that the conditions at Patea are comparable with those here? —They are infinitely better How far is the Patea channel cut out into the open sea?—lt is iust a natural channel. If a heavy easterly blow lasted for a week, what effect would it have on the Inner Harbour channel?—lt would depend to some extent on the slopes of the channel. The bottom would be agitated and scouring would be maintained. Providing that the sides of the channel were of the same slope as the sides of the dredged hole there would be no marked diminution of the depth of the channel. Would you allow a 500 ft. ship in after laying out during an easterly blow for a week without soundings being first taken ’—No ; they could be taken by the harbourmaster on his wav out in his launch.

Your dredged channel would be operated on by natural forces until the angle of its sides had varied from one in three to one in thirty-three Do you think that there would be a possibility while this process is going on of the depth being lessened ? —Yes; but it would be very gradual. Do these various considerations regarding the possibility of lessening the deapth raise any doubts as to you recommending this channel for use?— None whatever.

COMPARISON WITH PANAMA CANAL.

If the captain of a liner in the roadstead believed that there was a one per cent, risk of danger in the channel what would be his duty?—No boat would be launched if no risks were to be taken. At the Panama Canal, on the Atlantic side, there is a channel 5} miles long and 500 ft. wide. It is being negotiated every day by vessels similar Jo those coming to Napier, and I have not heard of any accidents occurring in that channel. The entrance to the Panama channel is out to sea. If the captains can navigate that channel under the conditions that obtain there, there should be no difficulty in navigating the channel here. Panama channel is navigated at night as well as by day. Does the statement by Messrs. Maxwell, Williams and Mason regarding the possibility of the silting up of the channel causing great inconvenience to shipping create any doubt in your mind?—No, not the slightest, when taking into account what is being done elsewhere, and further, seeing that they had not taken into account the grinding of the shingle of the beach.

Mr. Gray: I would suggest that the witness be asked as to whether the Whakariri was engaged to dredge a patch after that report. Mr. Holmes: That was the position.

Mr. Holmes then put in a photograph of the Breakwater taken in 1892, showing a heavy wave breaking across the entrance.

Mr. Holmes, in considering the risk of the steering gear being limited to the rudder, said that the heavier sea at the Breakwater would deliver a heavier impact against the vessel, and calculated that the risk of a 12ft. wave at the Breakwater would be 2} times greater than a seven-foot wave at the Inner Harbour. Mr. Waters: You recognise that the value of the reclaimed areas and the rentals to he derived is the crux

of the whole question of harbour construction from the financial point of view?—No. They are very lucky to have the areas to reclaim in order to be able to recoup themselves. As far as I can follow the sum of £319,400 has been put down as a credit for reclaimed land in connection with the Inner Harbour scheme? —That is so.

Deducting the value of the reclaimed land from the cost of the harbour you arrive at the nett cost of £170,000. Do you still say that the reclaimed land is not the crux from the financial point of view?—Yes, a harbour should rely upon its dues. Reclamation is undoubtedly of great importance. Mr. Barton: You look upon the harbour dues as being of the greater importance?—Yes, I do. You realise that the interest on the cost of construction would be £30,000 annually l ?—Yes.

And this amount outside of rents would have to be raised by rates and dues?—Yes. If business men and the board’s officials do not think that these charges can stand increasing would that alter your opinion regarding reclamation ? — Reclamation rents must certainly come into it.

Did you notice that Cullen and Keele’s estimated the maintenance annually for the Inner Harbour would be £lO,OOO more than that for the Breakwater?—l didn’t read it that way. They qualified it later by a lettbr. Have you prepared estimates for the maintenance of these two harbour proposals?—No, MAINTENANCE ESTIMATES. Mr. Barton intimated that unless maintenance estimates were furnished the commission would be obliged to comment upon the fact that estimates were supplied of harbour pro posals without those for the expected maintenance being placed before them.

Mr McKenzie: Assuming the channel was dredged to 34ft, what draught of vessels would assist the scour? — Twenty-five feet draught boats. I would assume then to steam 10 knots on entering.

Over a period of two years 116 vessels anchored in the roadstead, while at the Breakwater 46 were berthed, during a similar period, an average of 81 vessels per year, which means that on 284 days you could only rely on the scouring action by vessels?—l may point out that such an action would assist- There are other factors as well.

Mr Gray: They would be going out as well. Mr McKenzie: That is it. The number of days would be reduced to half.

Mr. Gray: A number of these vesseis would be drawing 25ft? I think the propellers of a vessel drawing 20ft would have an effect on the bottom. Where is there that particular type of swivell-head dredge you referred to in New Zealand?—There is one at Lyttelton. When did you first suggest using a swivell-head for the channel?—That has been aur idea all through. My idea w.»s to use the Kaione.

What would be the cost of fitting such a swivel head?—£looo. That has been allowed for in the estimates. How is it fitted?—Some section of it is on a ball and socket joint. It was not the suggested use of the swivel-head that has made the difference between working on an 18in. lift and a 3ft. lift, but a variation in the angle of the dredging arm.